Group-based beam management

ABSTRACT

A WTRU may include a memory and a processor. The processor may be configured to receive beam grouping information from a gNB or transmission and reception point (TRP). The beam grouping information may indicate a group of beams that the WTRU may report using group-based reporting. The group-based reporting may be a reduced level of reporting compared to a beam-based reporting. The group-based report may include measurement information for a representative beam. The representative beam may be one of the beams in the group or represents an average of the beams in the group. Alternatively, the representative beam may be a beam that has a maximum measurement value compared to other beams in the group. The group-based report may include a reference signal received power (RSRP) for the representative beam and a differential RSRP for each additional beam in the beam group.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/953,469 filed Nov. 20, 2020 which is a continuation of U.S. patentapplication Ser. No. 16/347,065 filed May 2, 2019, now U.S. Pat. No.10,848,232 which is the national stage of International Application No.PCT/US17/059806 filed Nov. 2, 2017 and which claims the benefit of U.S.Provisional Patent Application No. 62/416,674, filed Nov. 2, 2016, U.S.Provisional Patent Application No. 62/443,288, filed Jan. 6, 2017, U.S.Provisional Patent Application No. 62/500,792, filed May 3, 2017, U.S.Provisional Patent Application No. 62/519,621, filed Jun. 14, 2017, U.S.Provisional Patent Application No. 62/542,950, filed Aug. 9, 2017, thecontents of which are incorporated by reference.

BACKGROUND

In next generation mobile communications, applications such as enhancedmobile broadband (eMBB), massive Machine Type Communications (mMTC) andUltra-Reliable Low Latency Communications (URLLC) may be deployed. Awide range of spectrum bands ranging from 700 MHz to 80 GHz may be usedin a variety of deployment scenarios. These may include both licensedand unlicensed spectrum.

Multiple antenna transmission and beam firming may be used. For sub-6GHz transmission, multiple antenna techniques such as Multiple InputMultiple Output (MIMO) transmission and its different flavors, e.g.,Single Input Multiple Output (SIMO) and Multiple Input Single Output(MISO) techniques may be used. Different MIMO techniques may deliverdifferent benefits such as providing diversity gain, multiplexing gain,beamforming, array gain, etc. In the cellular communication, where UTsmay communicate to a single central node, the use of MU-MIMO mayincrease the system throughput by facilitating the transmission ofmultiple data streams to different UTs at the same time on the sameand/or overlapping set of resources in time and/or frequency. In theSU-MIMO case, the same central node may transmit multiple data streamsto the same UT.

SUMMARY

One or more example embodiments as described more fully below provideapparatuses, functions, procedures, processes, execution of computerprogram instruction tangibly embodying a computer readable memory,functions and operation of methods for one or more of the following.Systems, methods, and instrumentalities may be provided for beamgrouping, group-based beam management, signalling group-based beamindication, group-based beam reporting, group-based beam tracking and/orpairing and waveform selection for beam management.

For example, multiple transmission or receiving beams may be groupedinto a beam group. The grouping may be based on one or more of spatialcorrelation measurement, a pre-defined rule and/or procedure, or abeamwidth of the transmission beams. When a transmission and receptionpoint (TRP) creates the beam group(s), an indication of the grouping toa wireless transmit/receive unit (WTRU). The WTRU may perform per beamand/or per-beam group based measurements, and send the measurements tothe TRP. Upon receiving the measurements, the TRP may update the beamgrouping based on the measurements.

The WTRU may include a memory and a processor. The processor may beconfigured to receive beam grouping information from a transmission andreception point (TRP). The beam grouping information may indicate agroup of beams that the WTRU may report using group-based reporting. Thegroup-based reporting may be a reduced level of reporting compared to abeam-based reporting. The group-based report may include measurementinformation for a representative beam. The representative beam may beone of the beams in the group or represents an average of the beams inthe group. For example, the representative beam may be a beam that has amaximum measurement value compared to other beams in the group. Thegroup-based report may include a reference signal received power (RSRP)for the representative beam and a differential RSRP for a different beamin the beam group.

The beam-based report may include measurement information for individualbeams. The group-based report may have less information about individualbeams than the beam-based report.

The WTRU may send, to the TRP, a group-based report during a short cycleand a beam-based report during a long cycle. The WTRU may send, to theTRP, the group-based report, via uplink (UL) signaling periodically oraperiodically. When the group-based report is sent periodically, it issent using NR-physical control uplink channel (PUCCH). When thegroup-based report is sent aperiodically, it is sent using NR-physicaluplink shared data channel (PUSCH) The processor may be configured tosend the group-based report more often than the beam-based report.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment;

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment;

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment;

FIG. 2 depicts an example Transmission/Reception Points (TRP) and a WTRUantenna model.

FIG. 3A depicts two example groups of beams with different equalbeamwidths.

FIG. 3B depicts two example groups of beams with unequal beamwidths thatmay be used in scenarios with unequal distribution of WTRUs within theTRP.

FIG. 4A depicts an example downlink (DL: group-based beam management.

FIG. 4B depicts an example DL group-based beam management.

FIG. 5 depicts an example DL group-based beam management.

FIG. 6 depicts an example beam group.

FIG. 7 depicts an example beam group affected by a blockage.

FIG. 8 depicts an example beam group affected by a WTRU rotation.

FIG. 9 depicts an example message call flaws for beam group generation,reporting, and/or maintenance.

FIG. 10 depicts an example message call flows for beam group generation,reporting, and/or maintenance for the case of multiple TRPs.

FIG. 11 depicts an example use of a different modulation type forpunctured data.

FIG. 12 depicts an example multi-beam transmission system.

FIG. 13 depicts an example per beam transmission of an identificationsequence.

FIG. 14 depicts an example beam-group identification by puncturingpattern,

FIG. 15 depicts an example beam-group identification through a waveform.

FIG. 16 depicts an example a process for beam-group identification.

FIG. 17 depicts an example beam group with a representative beam(s).

FIG. 18 depicts an example beam-pair group with a representativebeam-pair(s).

FIG. 19 depicts an example composite beam.

FIG. 20 depicts an example of a transmission beam-pair group(s).

FIG. 21 depicts an example of a measurement beam group(s).

FIG. 22 depicts an example P-1/U-1 bean management process (e.g.,procedure), including identifying beam of angular spread 90 degrees.

FIG. 23 depicts an example P-2/P-3/U-2/L-3 beam management process(e.g., procedure) group 1 having 4 beams per P-1 beam with angularspread 22.5 degrees.

FIG. 24 depicts an example P-2/P-3/U-2/L-3 beam management process(e.g., procedure) group 2 having 4 beams per group 1 beam with angularspread 5.625 degrees.

FIG. 25 depicts an example P-2/P-3/U-2/L-3 beam management process(e.g., procedure) group 3 having 4 beams per group 2 beam with angularspread 1.046 degrees.

FIG. 26 depicts an example P-2/P-3/U-2/L-3 beam management process(e.g., procedure) group 1 group with unequal beamwidth.

FIG. 27 depicts an example P-2/P-3/U-2/L-3 beam management process(e.g., procedure) group 2 group with unequal beamwidth (and higherresolution than group 1 shown in FIG. 26 ).

FIG. 28 depicts an example P-2/P-3/U-2/L-3 beam management process(e.g., procedure) group 1/2 group with unequal beamwidth.

FIG. 29 depots an example P-1 beam management process (e.g., procedure).

FIGS. 30A-30B depict an example group based L1/L2 beam managementprocess (e.g., procedure) for P-2/P-3/U-2/L-3 beam refinement.

DETAILED DESCRIPTION

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a RAN104/113, a CN 106/115, a public switched telephone network (PSTN) 108,the Internet 110, and other networks 112, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 102 a,102 b, 102 c, 102 d may be any type of device configured to operateand/or communicate in a wireless environment. By way of example, theWTRUs 102 a, 102 b, 102 c, 102 d, any of which may be referred to as a“station” and/or a “STA”, may be configured to transmit and/or receivewireless signals and may include a user equipment (UE), a mobilestation, a fixed or mobile subscriber unit, a subscription-based unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watchor other wearable, a head-mounted display (HMO), a vehicle, a drone, amedical device and applications (e.g., remote surgery), an industrialdevice and applications (e.g., a robot and/or other wireless devicesoperating in an industrial and an automated processing chain contexts),a consumer electronics device, a device operating on commercial and/orindustrial wireless networks, and the like. Any of the WTRUs 102 a, 102b, 102 c and 102 d may be interchangeably referred to as a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106/115, the Internet 110and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an eNode B,a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, anaccess point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104/113, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one of morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA. TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104/113 and the WTRUs 102 a,102 b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 115/116/117 using wideband CDMA (WCDMA).WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink (Dl) Packet Access (HSDPA) and/or High-Speed UL Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a Radio technology such as NR Radio Access which mayestablish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., a eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CCMA2000, CDMA2000 1×, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000. GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106/115.

The RAN 104/113 may be in communication with the CN 106/115, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. The data may have varying qualityof service (QoS) requirements, such as differing throughputrequirements, latency requirements, error tolerance requirements,reliability requirements, data throughput requirements, mobilityrequirements, and the like. The CN 106/115 may provide call control,billing services, mobile location-based services, pre-paid calling.Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or theCN 106/115 may be in direct or indirect communication with other RANsthat employ the same RAT as the RAN 104/113 or a different RAT. Forexample, in addition to being connected to the RAN 104/113, which may beutilizing a NR radio technology, the CN 106/115 may also be incommunication with another RAN (not shown) employing a GSM, UMTS, COMA2000 WiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also serve as a gateway for the WTRUs 102 a, 102 b,102 c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP Internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104/113 or a different RAT.

Some or allot the WTRUs 102 a, 102 b, 102 c, 102 d in the communicationssystem 100 may include multi-mode capabilities (e.g., the WTRUs 102 a,102 b, 102 c, 102 d may include multiple transceivers for communicatingwith different wireless networks over different wireless links). Forexample, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. II will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible right signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 18 as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled b the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WRTU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116 In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160 b, 160 c may communicate with one another over an X2 interface

The CN 106 shown in FIG. 1C may induce a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 136, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 1026, 102 c, managing and storing contexts of the WTRUs102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 1026, 102 c and traditionalland-line communications devices, for example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in to and/or out of the BSS. Traffic to STAs that originatesfrom outside the BSS may arrive through the AP and may be delivered tothe STAs. Traffic originating from STAs to destinations outside the BSSmay be sent to the AP to be delivered to respective destinations.Traffic between STAs within the BSS may be sent through the AP, forexample, where the source STA may send traffic to the AP and the AP maydeliver the traffic to the destination STA. The traffic between STAswithin a BSS may be considered and/or referred to as peer-to-peertraffic. The peer-to-peer traffic may be sent between (e.g., directlybetween) the source and destination STAs with a direct link setup (MS).In certain representative embodiments, the DLS may use an 802.11e DLS oran 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS)mode may not have an AP, and the STAs (e.g., all of the STAs) within orusing the IBSS may communicate directly with each other. The IBSS modeof communication may sometimes be referred to herein as an “ad-hoc” modeof communication.

When using the 802.11ac infrastructure made of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMAICA) may be implemented, for example in in 802.11systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, maysense the primary channel. If the primary channel is sensed/detectedand/or determined to be busy by a particular STA, the particular STA mayback off. One STA (e.g., only one station) may transmit at any giventime in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac, 802.11afsupports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications, such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 10 is a system diagram illustrating the RAN 113 and the CN 115according to an embodiment. As noted above, the RAN 113 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116 The RAN 113 may also be in communication with theCN 115.

The RAN 113 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 113 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a, In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a, 184 b, routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 115 shown in FIG. 1D may induce at least one AMF 182 a, 182 b, atleast one UPF 184 a, 184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 115, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different PDU sessions with differentrequirements), selecting a particular SMF 183 a, 183 b, management ofthe registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182 a,182 b in order to customize CN support for WTRUs 102 a, 102 b, 102 cbased on the types of services being utilized WTRUs 102 a, 102 b, 102 c.For example, different network slices may be established for differentuse cases such as services relying on ultra-reliable low latency (URLLC)access, services relying on enhanced massive mobile broadband (eMBB)access, services for machine type communication (MTC) access, and/or thelike. The AMF 162 may provide a control plane function for switchingbetween the RAN 113 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected ban AMF 182 a, 182 b in the CN 115via an N11 interface. The SMF 183 a, 183 b may also be connected to aUPF 184 a, 184 b in the CN 115 via an N4 interface. The SMF 183 a, 183 bmay select and control the UPF 184 a, 184 b and configure the routing oftraffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b may performother functions, such as managing and allocating UE IP address, managingPDU sessions, controlling policy enforcement and QoS, providing downlinkdata notifications, and the like. A PDU session type may be IP-based,non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected b one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 115 and the PSTN 108. In addition, the CN 115may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a localData Network (DN) 185 a, 185 b through the UPF 184 a, 184 b via the N3interface to the UPF 184 a, 184 b and an N6 interface between the UPF184 a, 184 b and the ON 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d. Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-b, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation clavicles mayperform the one or more, or all, functions while being fully orpartially implemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

A WTRU may include a memory and a processor. The processor may beconfigured to receive beam grouping information from a gNB ortransmission and reception point (TRP). The beam grouping informationmay indicate a group of beams that the WTRU may report using group-basedreporting. The group-based reporting may be a reduced level of reportingcompared to a beam-based reporting. The group-based report may includemeasurement information for a representative beam. The representativebeam may be one of the beams in the group or represents an average ofthe beams in the group. Alternatively, the representative beam may be abeam that has a maximum measurement value compared to other beams in thegroup. The group-based report may include a reference signal receivedpower (RSRP) for the representative beam and a differential RSRP foreach additional beam in the beam group.

The beam-based report may include measurement information for individualbeams. The group-based report may have less information about individualbeams than the beam-based report.

The WTRU may send, to the TRP, a group-based report during a short cycleand a beam-based report during a long cycle. The WTRU may send, to theTRP, the group-based report, via uplink (UL) signaling periodically oraperiodically. When the group-based report is sent periodically, it issent using NR-physical control uplink channel (PUCCH). When thegroup-based report is sent aperiodically, it is sent using NR-physicaluplink shared data channel (PUSCH). The processor may be configured tosend the group-based report more often than the beam-based report.

Multiple antenna transmission at millimeter wave frequencies may differslightly from sub-6 GHz multiple antenna techniques. This may be due tothe different propagation characteristics at millimeter wave frequenciesand the possibility of the BTS/UE having a limited number of RF chainscompared with antenna elements.

The massive antenna model may be configured as Mg antenna panels pervertical dimension and Ng antenna panels per horizontal dimension,wherein a antenna panel may be configured with N column and M row ofantenna element with or without polarization as shown in the FIG. 2 .The timing and phase may be not calibrated across panels althoughmultiple panels may be equipped in the same eNB. The baseline massiveantenna configuration may be different according to the operatingfrequency band as listed in TABLE 1.

TABLE 1 Baseline massive antenna configuration for dense urban and urbanmacro At 4 GHz At 30 GHz At 70 GHz Dense urban and urban macro: Denseurban and urban macro: Dense urban: (M, N, P, Mg, Ng) = (8, 8, 2, 1, 1),(M, N, P, Mg, Ng) = (4, 8, 2, 2, 2), Baseline: (M, N, P, Mg, Ng) = (dV,dH) = (0.8, 0.5)λ (d_(V), d_(H)) = (0.5, 0.5)λ, (8, 16, 2, 2, 2),(d_(V), d_(H)) = (0.5, 0.5)λ, (d_(gV), d_(gH)) = (2.0, 4.0)λ (d_(gV),d_(gH)) = (4.0, 8.0) λ A single panel 4 panels 4 panels 64 elements perPol. 32 elements per Pol. 128 elements per Pol. Total 128 elements Total256 elements Total 1024 elements

Precoding at millimeter wave frequencies nay be digital, analog or ahybrid of digital and analog. Digital preceding may be precise and canbe combined with equalization. It may enable single user (SU),multi-user (MU) and multi-cell precoding and may be similar to that usedin sub 6 GHz, for example in IEEE 802.11n and beyond and in 3GPP LTE andbeyond. In millimeter wave frequencies, the presence of a limited numberof RF chains compared with antenna elements and the sparse nature of thechannel may complicate the use of digital beamforming. Analogbeamforming may overcome the limited number of RF chains issue by usinganalog phase shifters on each antenna element. It may be used in IEEE802.11ad during the sector level sweep (which may identify the bestsector), beam refinement (which may refine the sector to an antennabeam) and beam tracking (which may adjust the sub-beams over time totake into account any change in the channel) procedures.

In hybrid beamforming, the precoder may be divided between analog anddigital domains. A domain may have precoding and combining matrices withdifferent structural constraints e.g., constant modulus constraint forcombining matrices in the analog domain. This design may result in acompromise between hardware complexity and system performance. Hybridbeamforming may be able to achieve digital precoding performance due tosparse nature A channel and support multi-user/multi-streammultiplexing. It may be limited by number of RF chains. The mmWavechannels may be sparse in the angular domain.

Beam management for new radio may be performed. The use of higher bandfrequencies may imply that their propagation characteristics mayinfluence the system design. As frequencies increase, the channel mayexperience higher path losses and more abrupt changes. In high frequencybands, large-scale antenna array could be used to achieve highteamforming gain so as to compensate the high propagation loss. Theresulting coupling loss could be kept at high level to support thedesired data throughput or coverage. The use of directional bean basedcommunication may be associated with accurate beam pairing, and thecorrect beam direction may be associated with real channel, in terms ofangle of arrival and angle of departure in both azimuth and elevation.The correct beam direction may be dynamically adjusted with the channelchange.

Beam management may be performed on a per beam basis (or beam-by-beambasis). To reduce signalling/feedback overhead and allow certainflexibility of using beams for transmission/reception, group-based beamindication may be performed. Beam management may be performed on a groupbasis. Beam grouping can be performed at the TRP side and/or at the UEside. Group-based beam maintenance can be performed such that beamtracking/refinement within a group or multiple groups can be supportedin more transparent manner. Group-based beam switching can be supportedwhen multiple beam groups are maintained in order to improve therobustness against unexpected channel blockage. Beam grouping mayinclude, TRP(s) or UE may group multiple Tx and/or Rx beam(s) and/orbeam pair(s) into one subset of beams. Beam grouping, reporting,beam-group based indication for beam measurement, beam-basedtransmission and/or beam switching may be performed.

Beams may be grouped. The group-based beam capability may becommunicated. Beam-group based indication may be signalled. The WTRU mayperform group-based beam measurement and reporting. Group-based beamsweeping, pairing and tracking may be performed. Waveform selection forbeam management may be performed. NR may support DFT-S-OFDM basedwaveform complementary to CP-OFDM waveform, e.g., for eMBB uplink for upto 40 GHz. Low PAPR techniques may be employed. CP-OFDM waveform can beused for a single-stream and multi-stream (e.g., MIMO) transmissions.DFT-S-OFDM based waveform may be limited to a single streamtransmissions (targeting for link budget limited cases). Network maydetermine and communicate to the UE which one of CP-OFDM and DFT-S-OFDMbased waveforms to use. CP-OFDM and DFT-s-OFDM based waveforms may beused for UE The network may determine and communicate to the UE whichwaveforms to use for beam management.

The term gNB or eNB may be interchangeably used with transmission andreception point (TRP) hereof. A TRP may have one or multiple beams. AWTRU may have one or multiple beams. Beam management with one TRP may benamed as intra-TRP beam management, while beam management with multipleTRPs may be named as inter-TRP bean management.

A WTRU's capability of performing a group-based beam operation may beindicated via an information element (IE). For example, whether the WTRUis capable of performing single beam operations on per-beam basis,and/or whether the LE is capable of performing group-based beamoperations may be indicated in the WTRU's capability IE. The WTRU'scapability may be summarized in the WTRU's beam capability IE. Anexample of bean capability IE is shown in

ENUMERATED {beam, group-based beam, both, none, spare},

where “beam” may indicate that a WTRU supports single beam operations onper-beam basis including one or more of beam sweeping, beam reporting,or the like; “group-based beam” may indicate that the WTRU supportsgroup-based beam operations (e.g., one or more of the group-based beamoperations as discussed herein), both may indicate that the WTRUsupports both single-beam based operations and group-beam basedoperations; none may indicate that the WTRU does not support beam-basedoperations; “spare” may be reserved for future usage.

Group-based beam management (BM) for multiple TRPs may be performedusing one or more of transparent global group-based BM management,non-transparent localized group-based BM management, or beam and/or WTRUgrouping. For example, transparent global group-based BM management maybe used for multi-TRP. Which TRP a beam group is for may be transparentto the WTRU. A beam group(s) may be formed from a same beam set thatincludes beams (e.g., all beams) from TRPs (e.g., all TRPs), forexample, based on one or more of the criterion defined herein. Which TRPa beam within a beam group is for or associated with may not be requiredto be indicated (e.g., signaled) to the WTRU.

Non-transparent localized group-based BM may be used for multi-TRP.Which TRP a beam within a beam group is for or associated with may notbe transparent to the WTRU. A beam group may be formed from differentbeam sets from different TRPs, for example, based on any of thecriterion defined herein. Which TRP a beam within the beam group isassociated with may be indicated (e.g., signaled) to the WTRU.

Group-based BM may be used and/or configured for a group of WTRUs.Group-based BM may be transparent or non-transparent. A beam group maybe associated with a specific set of WTRUs. A signal may be sent (e.g.,implicitly sent) to a set of WTRUs to switch to a specific beamconfiguration. For example, this may configure and/or indicate abeam-group for a specific WTRU group which may include one or moreWTRUs.

In an example of group-based beam management for multiple TRPs, two TRPsmay be associated (e.g., connected) with one WTRU. TRP′ may have onebeam set with 6 Tx beams while TRP2 may have a beam set with 4 Tx beams.Beam group 1 may be formed with TRP1 Tx beam 5 and TRP2 Tx beam 1; beamgroup 2 may be formed with TRP1 Tx beam 2 and TRP1 Tx beam 3.

When transparent global group-based BM management is performed, thebeams from the TRPs may form a beam set (1, 2, 3, 4, 5, 6, 7, 8, 9, 10),If the beams from TRP1 and TRP2 are indexed in an ascending order, beamgroup 1 and 2 may be defined or signaled as {5, 7} and {2, 9}respectively.

When non-transparent localized group-based BM management is performed,the beams from different TRPs may form 2 beam set: TRP1 beam set {1, 2,3, 4, 5, 6} and TRP2 beam set {1, 2, 3, 4}. Beam groups 1 and 2 may bedefined or signaled as {TRP1.5, TRP2.1} and {TRP1.2, TRP2.3}respectively.

When transparent global group-based BM management is used with beam andWTRU grouping, beam groups 1 and 2 may be defined or signaled as {5,7,{UE1, UE3}} and {2.9, {UE5, UE7}} respectively. When non-transparentglobal group-based BM management is performed, and beam and WTRUgrouping is performed, beam groups 1 and 2 may be defined or signaled as{TRP1.5, TRP2.1, {UE1 UE3}} and {TRP1.2, TRP2.3, {UE5, UE7}}respectively.

Beams may be grouped based on various techniques. For example, beamgroups may be defined based on one or a combination of the followingcriterion.

Beam groups may be defined based on channel properties. TRP(s) orWTRU(s) may group multiple Tx/Rx beam(s) or beam pains) into one subsetof beams sharing similar channel properties and/or physical antennaarray properties. Beam grouping may be performed on Tx beams, Rx beamsand/or Tx-Rx beam pairs or beam pair links (BPLs) sharing similarchannel properties, such as angles of arrival (AoA) and/or angles ofdeparture (AoD). QCL, TA, polarization, or WTRU capability such as arrayor sub-array properties (e.g., WTRU front or back panel).

Spatial correlation measurement may be used to perform beam grouping. TXbeams (e.g., from an array or a sub-array) with spatial correlationmeasurement that is greater or less than a pre-defined threshold may begrouped into a same beam group. Beams with high spatial correlation mayhave similar AoD and/or polarization values, which may indicate highspatial correlation between the beams and/or that the beams arespatially close to each other. AoD and/or polarization may be used as ametric to measure spatial correlation. One or more baseline AoDs may beselected. The beams that have AoD difference less than a threshold fromone of the baseline AoD may be grouped into a Tx beam group with onepolarization, Rx beams with spatial correlation measurement greater thana pre-defined threshold may be grouped into a beam group. AoA and/orpolarization may be used as a metric to measure the spatial correlation.One or more baseline AoAs may be selected. The beams that have MAdifference less than a threshold to one of the baseline AoA may begrouped into one Rx beam group with one polarization. A beam pair link(BPL) may be based on joint AoDs/AoAs or spatial correlationmeasurements at both TX and RX.

A beam group may be defined and/or created based on a pre-defined ruleand/or procedure. The pre-defined rule may include parameters thatincludes a MIMO transmission type. A definition of the MIMO transmissiontype may support one or more d: multiple WTRUs and/or multiple TRPscommunicating over a same set of sub-band frequencies (e.g.,sub-carriers, or resources). Multiple WTRUs and/or multiple TRPscommunicating over a same set of sub-band frequencies may also bereferred to as MU-MIMO or multi-user MIMO. MU-MIMO or multi-user MIMOmay include one or more of the following: a single TRP to multipleWTRUs, transmission form multiple WTRUs to a single TRP, transmissionfrom multiple TRPs to a single WTRU, and/or transmission from multipleTRPs to multiple WTRUs. The pre-defined rule may depend on transmissionrequirements and or capabilities including one or more of initialaccess, re-association, handover, a MIMO transmission capability, a usecase (e.g., including one or more of eMBB, mMTC, URLLC, or the like), ora service type (e.g., including one or more of video, VoIP, gaming, orthe like).

A definition of beam groups may be implemented using approaches herein.Bean groups may be defined using a similar link budget for cell centerand/or a cell edge. Beam groups may be defined using mobility rules thatmay recommend a wide beamwidth to support a high mobility and/or abroader coverage. Beam groups may be defined by a common spatial region,using a sector defined in one or more of azimuth, elevation, an antennaarray or subarray, or polarization.

The beam group may be defined based on the beamwidth of the beam by aWTRU or TRP enabling grouping a set of beams. For example, a WTRU or TRPthat is undergoing a beam-sweep procedure may decide to group a set oftransmit or receive beams. For example, an L1/L2 beam managementprocedure may sweep through a series of beamwidths to identify a refinedbeam (e.g., the best refined beam). The WTRU may identify a set ofdesired beams within a (e.g., each) beamwidth as a single group byfeeding back details of the beams and/or a beam group ID. The beam groupID may be unique.

A set of beams with equal beam widths that span the beam subspace may beidentified as a group. FIG. 3A illustrates a set of beams having equalbeam widths that span the beam subspace as a group. A set of beams thatspan a portion of the beamspace with unequal beamwidths may beidentified. FIG. 38 illustrates a set of beams that span a portion ofthe beamspace with unequal beamwidths. Grouping in this manner (e.g.,grouping in the manner shown in FIG. 3A and FIG. 3B) may facilitate anL1/L2 beam management procedure to identify the best transmit/receivebeams for transmission. In multi-beam transmission, sub-beam groupingwithin a sweep group may be used to identify sub-groups that maytransmit simultaneously for more efficient beam sweeping.

Beam groups may be determined, indicated, and/or configured. One or morebeam groups may be determined and used at a WTRU receiver (Rx), forexample, based on one or more of the criterion herein. A beam group maybe determined based or one or more of the following. One or more Rxbeams which may be formed or received simultaneously may form a beamgroup. The maximum number of beam groups may be referred to as M. Themaximum number of Tx beams reported for a beam group may be referred toas N. The number of beam groups to report at a time may be referred toas L. The number of Tx beams reported for a beam group at a time may bererred to as Q. M and/or N may be indicated by WTRU capability IE. Land/or Q may be configured by, for example, one or more of RRC message.MAC-CE, or DCI control signaling.

A WTRU may report or indicate the number of beam groups supported at theWTRU. A WTRU may report or indicate the maximum number of beam groups M′(for example, M′≤M), and the WTRU's associated beam group information. AWTRU may request M′ beam groups' sounding reference signal (SRS)resources to provide information of beam groups when a WTRU has beamcorrespondence capability. For example, each SRS resource may be used totransmit Tx beams which may correspond to RX beams in an associated beamgroup. A gNB may receive or pair the RX beams based on each SRSresource(s) (e.g., beam group), and the gNB may determine Tx beams foreach Rx beam group.

A WTRU may report or indicate beam group information (e.g., each beamgroup information) based on a set of CSIRS resource indices. A firstteam group may be associated with a first set of CSI-RS resources and asecond beam group may be associated with a second set of CSI-RSresources. A gNB may indicate a beam group for a downlink transmission,and a WTRU may determine Rx beam group for downlink reception based onthe indication, A WTRU may autonomously determine the beam groups and/orindicate (e.g., only indicate) the number of beam groups used orsupported at the WTRU.

A WTRU may report some Tx beams for each of a certain number of beamgroups. A WTRU may report Q Tx beams for each of L beam groups, whereinQ and L may be determined based on one or more of the following. If L=1,a WTRU may determine a beam group which may provide at least one of ahighest SNR, a highest throughput performance, a highest CQI, or ahighest RSRP among the beam groups supported at the WTRU. A WTRU maydetermine a beam group which may be indicated in the DCI. The DCI may beused to trigger the Tx beams reporting. A WTRU may determine a beamgroup which may be associated with a specific antenna group (forexample, a panel associated with the TRP). The beam group index may bereported when the associated Q Tx beams are reported. Q Tx beams whichmay be determined for the determined beam group may be reported.

If L>1, a WTRU may determine L beam groups which may provide at leastone of the highest L SNRs, the highest L throughput performances, thehighest L CQIs, or the highest L RSRP among the beam groups supported atthe WTRU, A WTRU may determine L beam groups which may be associatedwith a specific antenna group (for example, a panel associated with theTRP). For example, the best L beam groups may be reported and/or Q Txbeams for each of the best L beam groups may be reported. Q may bedifferent based on the beam group. For example, Q(I) may be reported,where I may be a beam group index.

L may be determined based on at least one of the following: the WTRUcapability (for example, M′), the transmission mode, the uplink channelused for Tx beam reporting (for example, L=1 may be used if PUCCH isused for the beam reporting and L>1 may be used if PUSCH is used for theTX beam reporting), the reporting periodicity (for example, L=1 may beused for periodic or semi persistent Tx beam reporting and L>1 may beused fa aperiodic beam reporting), or one or more of the number of CSIreport settings configured, the number of resource settings configured,and the number link. L may be configured via higher layer signalling.

The Q for a beam group may be determined based on at least one of thefollowing. The Tx beams for a beam group may be determined or selectedby a WTRU based on QCL status. For example, a WTRU may determine Txbeams for a beam group among the Tx beams which may be QCL-ed for one ormore QCL parameters (e.g. QCL parameters except for special Rxparameters, which may be referred to as a QCL type). The Tx beams for abeam group may be determined or selected by the WTRU based on a Tx beamgroup. For example, one or more Tx beam groups may be defined, and aWTRU may determine a Tx beam group for an Rx beam group.

Group-based beam management may be provided. DL group-based beammanagement may be provided. FIG. 4A shows example downlink (DL)group-based beam management. Group based beam management may beperformed in L1 and/or L2. A multi-beam approach may be applied in orderto increase network coverage by exploiting MIMO and beamforming gain.The rules, criteria or definition of beams, beam groups, and/orreciprocal beams may be enabled via dynamic signalling such as L1/2control channel with configurable short or long periodicities or viasemi-statically signalling e.g., in L3, The formation of beams may beperformed using hybrid beamforming wherein slow analog beamforming maybe used to create broad beams, and digital beamforming may be used tocreate fast narrow beams within an area of coverage of the analogbeam(s). Beam refinement and/or beam group refinement may depend on theusage scenario and/or associated requirements.

A beam pair (BP) or beam pair link (BPL) may include a single DL beamwith a single UL beam. A beam pair association (BPA) may include thediscovery, identify, pairing, tracking and maintenance of a DL/UL beamwith a UL/DL beam. A beam group (BG) may include two or more beams thathave been identified as belonging to one another for a TRP am/or a WTRU.A BG may include beams from more than one TRP. A beam ID may be definedfor an (e.g., each) instantiation of a beam, for example, for one ormore of instance where a beam is used and/or described. A beam ID mayinclude information pertaining to the TRP(s) and/or a WTRU to which thebeam ID belongs. A BPA may include one or more of the followingcharacteristics: rank, polarization, angle of arrival/departure. AoA/AoDspread, quasi-co-location (QCL), beamforming type(analog/digital/hybrid), coverage (omni/Sector, wide/narrow beam, etc.),and/or mobility metric. DL group based beam management may include a TRPprocess and/or a WTRU process. If there are more than one TRP, the TRPprocess may be coupled among the TRPs. A beam sweep (BS) may include aset of CSI-RS antenna ports, and/or beamformed transmissions may be usedto facilitate measurement of individual beam characteristics at the WTRUand/or the TRP. A TRP, gNB or BS may be preceded on the CSI-RS antennaports, and may use analog beamforming.

DL group based beam management may A enabled through measurement(s) atthe WTRU of one or more BPAs. These measurements may be initiated and/orrequested by the TRP. These measurements may be performed by the WTRU,for example, using one or more criterion defined by a process at theTRP.

The WTRU may perform measurement. The WTRU may perform BPA measurementsassociated with individual beams, and/or BPs. A measurement may includeone or more or all of, but not limited to: beam rank, beam polarization,mean angle-or-arrival, angle-of-arrival spread, beamforming type e.g.,analog, or hybrid, antenna WTRU port(s), mobility metric, or angularsector spread.

The WTRU may report a beam and/or beam pair (BP) measurement. A report(e.g., a single report) may be sent for a BP that may include theaggregated measurements on two or more beams. The aggregatedmeasurements may include the mean of individual beam measurements.

A BP may include an anchor beam or bean pair (ABP), and associatedsecondary beam(s) or beam pair(s) (SBP). The beam measurements may belargely determined by the anchor beam or beam pair characteristics. Thesecondary beam(s) or bean pair(s) may be used for incremental refinementof a BP measurement report.

A beam group process may be used. When a TRP receives the BPAmeasurement, the TRP may create one or more beam groups using one ormore criterion such that requirements for a (e.g., each) WTRU in aparticular usage scenario is accounted for. The beam groups may becreated based on the BPA measurements described herein. For example, arank indicator (RI) may be used. If the rank indicator (RI) is low (e.g.LOS channel) the maximum number of beam pairs (e.g. two associatedbeams) may be two. A larger rank may dictate a larger number ofavailable BPAs. The mean angle-of-arrival and/or angle-of-arrival spreadmay utilize QCL established between antenna ports, for example, tominimize the overhead of the measurement report(s). A beam group maybelong to a particular analog beam ID. There may be one or more beamgroups belonging to an analog beam ID. A mobility metric may determinestability of a particular beam group definition. A high mobility metricmay imply that a fallback to an associated analog beam may be used(e.g., in case that loss of BPA occurs).

Beam group information may be used. Beam group information may includethe TRP and/or WTRU IDs. A beam group may include a beam group belongingto a WTRU and/or a WTRU group ID. A beam group may include an anchorbeam and associated secondary beams. A beam group which contains ananchor beam may be referred to as an Anchor Beam Group Pair (BPA). Beamgroup information may be reported periodically or a-periodically. Thetime/frequency resource for the a-periodic report may be inducted in thebeam group information.

A beam group may be defined using resources that are defined (e.g.,uniquely defined) for a (e.g., each) beam group, for example, tofacilitate that mitigation of interference. In this way, a (e.g., each)beam group may expect to experience a different interference level, andthe subsequent WTRU report may enable the TRP to identify beam groupswith desirable characteristics.

A WTRU report may be used. The WTRU report may be configured to minimizefeedback overhead. A beam pair report may include a quality report whichis associated with a particular beam pair ID. The report may include oneor more of RI, RSRP, or CQI. A report may be associated with ahierarchical definition of the beam pair ID. The beau pair ID may belongto an associated hierarchy. In the case of blockage, the WTRU report mayinclude information which allows a fallback to an associated beam and/orbeam pair. Beam group information may be updated periodically, forexample, using information from the TRP. A periodic update may includeall or a subset (e.g., only a subset) of the beam group information.Information from the TRP and/or an approach may be configured, forexample, to trigger a-periodic WTRU report.

A beam group indication may be used. A beam group indication may beindicated to the WTRU explicitly and/or implicitly. An explicitindication may use associated beam group ID for indication. In the caseof beam reciprocity, a CSI-RS configuration may be used for the beamgroup indication.

A beam group indication may be updated. In the event that blockage or asimilar beam impairment occurs, the beam group indication may beupdated. If an anchor beam is defined, and the anchor beam is notimpaired, the anchor beam may be used to associate with an alternativesecondary beam. In this case the beam group indication may re-use theresources for the anchor beam. If an anchor beam is compromised, asecondary beam may be predefined as a fallback beam.

DL group-based beam management may be performed. FIG. 4A is an exampleof group-based beam management.

At 402, a WTRU may perform measurement(s). The measurement(s) may bebased on individual beam or beams, e.g., per-beam based measurement. Themeasurement may be based on beam pairs. e.g., per-beam pair basedmeasurement. The WTRU may report the measurement either per-beam based,per-beam pair based or using a combination of them.

At 404, a TRP may start forming a beam group(s), for example, based onWTRU reports or measurements, when the TRP receives the measurements(e.g., per-beam, per-beam pair) that are reported from WTRU. The TRP maystart forming abeam group(s), for example, based on TRP(s)'smeasurement. For example, the formation of beam groups may be determinedbased on the TRP's own and/or gNB's measurements or inputs (e.g.,interference conditions, traffic conditions, etc.). The formation ofbeam groups may be determined based on other TRP or gNB's measurementsor inputs (e.g., interference conditions, traffic conditions, etc.) whenmultiple TRPs are considered. The formation of beam groups may bedetermined based on some predetermined or configured criteria or rules(e.g., as described herein).

At 406, beam group information may be indicated to the WTRU when thebeam groups have been formed, for example, using dynamic signalling suchas L1/2 signalling or semi-static signalling such as RRC signalling. Theindication for the beam grouping may be implicit or explicit, forexample, using the techniques and/or approaches described herein. Forexample, indication approaches using semi-static signalling may use theRRC signalling for RRC procedures and messages for group-based beammanagement as described herein. Indication approaches using explicitapproaches may use the explicit group-based beam management signallingfor mechanisms for explicit group-based beam indication as describedherein. Indication approaches using implicit approaches may use theimplicit group-based beam management signalling for mechanisms forimplicit group-based beam indication as described herein. A combinationof implicit and explicit indication approaches may be performed.Combination of dynamic L1/2 signalling and semi-static RRC signallingmay be implemented Combination of implicit and explicit indicationapproaches via either L1/2 approaches and/or higher layer approach maybe performed.

At 408, when the WTRU receives the indication for group-based beammanagement information, the WTRU may start the measurement (e.g., ameasurement different from a current or previous measurement) andreporting based on the group-based beam management information and/orbeam group information.

At 410, WTRU measurement and reporting may use the approaches describedherein for group-based beam reporting. Beam group information may beupdated periodically.

At 412, the TRP may be triggered to update beam group informationaperiodically. The TRP may be requested to update beam group informationby a WTRU, TRP, gNB, or anchor cell. The TRP may be triggered to updatebeam group information by a different TRP (e.g., other TRP or TRPs thanthe TRP). The WTRU may suggest beam group information and/or send thesuggested beam group information to the TRP or gNB. The reporting hereinmay be aperiodic.

At 414, the indication of a different or updated beam group may beindicated to the WTRU using the implicit or explicit approachesdescribed herein. For example, when a different (e.g., different fromthe current or previous) beam group is formed. The WTRU may indicatedexplicitly via signalling or implicitly based on preset rules.

At 416, the WTRU may report measurement based on the different orupdated beam group information.

DL group-based beam management may be performed. FIG. 4B shows anexample DL group-based beam management. At 418, a WTRU may perform themeasurement during initialization. The measurement may be based onindividual beam, beams or beam pairs. The WTRU may report (e.g.,beam-based reporting) the measurement per-beam based, per-beam pairbased or combination of them, for example, via NR-PUSCH.

At 420, when a TRP receives the measurement(s) (e.g., per-beam, per-beampair) that is reported from the WTRU, the TRP may start forming one ormore beam groups based on WTRU's reports or measurements. The beamgroups may be determined based on the TRP's own or gNB's measurements orinputs (e.g., interference conditions, traffic conditions, etc.). Thebeam groups may be determined based on a different TRP(s)'s (e.g., TRPsother than the TRP) or gNB's measurements or inputs (e.g., interferenceconditions, traffic conditions, etc.) when multiple TRPs are considered.The formation of beam groups may be determined based on somepredetermined or configured criteria or rules as described herein.

At 422, the beam group information may be indicated to the WTRU, forexample, using dynamic signalling via NR-PDCCH or NR-ePDCCH with DCI,MAC or MAC CE, or RRC signalling. The beam group information may beindicated to the WTRU implicitly, for example, based on some presetrules.

At 424, the WTRU may start a different (e.g., different from a currentor previous) measurement and reporting for group-based beam management.The different measurement and reporting for group-based beam measurementand reporting may be different from non-group based (e.g., per-beam orbeam-based reporting) beam measurement and reporting. A short cycle maybe used to start reporting the different measurement. A short cycle maybe configured. For example, the WTRU may be configured with differentbeam reporting cycle or different periodicities (e.g., short or longcycles or periodicities). During short cycles, a reduced WTRU reportbased on beam group information (e.g., group-based reporting) may betransmitted. The group-based reporting may be associated with a reducedlevel of reporting comparing to a level of reporting associated withbeam-based reporting. The reduced WTRU report based on beam groupinformation may be transmitted via UL signaling periodically oraperiodically for example, periodically using NR-PUCCH or aperiodicallyusing NR-PUSCH or MAC-CE, for example where the reduced WTRU reportassociated with the short cycle is a reduced level of reporting comparedto a level of reporting associated with a long cycle.

At 426, the WTRU may reset the measurement and reporting for group-basedbeam management. A different cycle (e.g., a long cycle) from the shortcycle may be used to start resetting the measurement. For example, thelong cycle may include one or more short cycles. During a long cycle, aWTRU report based on individual beam(s) or beam pair(s) (e.g., abeam-based report (e.g., reporting based on configured or non-configuredone or more individual beams or reporting via a non-group-basedreporting), a report that is not reduced, or a full report) may betransmitted via UL signalling periodically or aperiodically. Forexample, the beam-based report may be transmitted via NR-PUCCH orNR-ePUCCH periodically, for example, every N short cycles. Thebeam-based report may be transmitted less often than the group-basedreport. The beam-based report may be triggered or requested andtransmitted via NR-PUCCH or NR-ePUCCH aperiodically.

At 428, beam group information may be updated, for example, based on areception of the beam-based report and measurements (e.g., per beam orper beam pair).

At 430, the updated beam group information may be indicated to the WTRU,for example, using dynamic signalling via NR-PDCCH or NR-ePDCCH withDCI, MAC or MAC CE, or RRC signalling. The updated beam groupinformation may be indicated to the WTRU implicitly, for example, basedon some preset rules.

At 432, the WTRU may report and/or measure based on different or updatedbeam group information on a per beam group basis (e.g., group-basedreporting).

UL group-based beam management may be performed. FIG. 5 illustrates anexample of UL group-based beam management if channel reciprocity or beamreciprocity/beam correspondence is available. At 502, a TRP may performthe measurement for an individual beam(s) or beam pair(s) that aretransmitted from a WTRU. At 504, a beam group(s) may be formed accordingto the TRP measurement. A beam group(s) may be formed based on some WTFUreport(s) or WTRU request(s). Formation of beam group may be determinedbased on some predetermined rules or configured criterion.

At 506, beam group information may be indicated to the WTRU, forexample, using implicit or explicit approaches such as those approachesdescribed herein. For example, indication approaches using semi-staticsignalling may use RRC signalling for RRC procedures and messages forgroup-based beam management as described herein. Indication approachesusing explicit approaches may use explicit group-based beam managementsignalling, for example, as described herein. Indication approachesusing implicit approaches may use implicit group-based beam managementsignalling for mechanisms for implicit group-based beam indication, forexample, as described herein. A combination of implicit and explicitindication approaches may be performed. Combination of dynamic L1/2signalling and semi-static RRC signalling may be implemented.Combination of implicit and explicit indication approaches via L1/2approaches and/or a higher layer approach may be performed.

At 508, a different WTRU transmission (e.g., different from the currentor previous one) may be performed, for example, based on reception ofthe beam group information.

At 510, beam group reciprocity may be indicated to the WTRU. At 512,WTRU transmission and/or reception may be performed based on thereception of beam group information including beam group reciprocity.

A group-based beam indication(s) may be used. The group-based beamindication(s) may be used for beam measurement, beam-based transmission,and/or beam switching. The group-based beam indication(s) may be (e.g.,explicitly) signalled to the WTRU, for example, via RRC message. MAC CEor NR-(e)PDCCH/NR-DCI, or implicitly based on some pre-defined rules.

Processes and messages for group-based beam indication(s) may be used.Impact(s) of WTRU mobility, WTRU rotation, and/or blockage on beamgroups may be considered. FIG. 6 may be a DL transmission exampleshowing the impacts of the WTRU mobility, WTRU rotation, and/or blockageon beam groups. As shown in FIG. 6 , there are 10 Tx Imams at the TRP,and 4 Rx beams at the WTRU. TRP's Tx beams 2 and 3 may have a similartransmission path(s) to the WTRU, and the TRP's Tx beams 2 and 3 may bereceived by the WTRU's Rx beam 1. TRP's Tx beams 4 and 5 may havesimilar transmission path to WTRU, and the TRP's Tx beams 4 and 5 may bereceived by WTRU's RX beam 4. In this example, the beam group 1 mayinclude Tx beam {2.3}, and Rx beam {1}, and the Tx beam group 2 mayinclude Tx beam {4,5} and Rx beam {4}.

The beam group may be affected by the blockage. As shown in FIG. 7 . acar may block the TRP's TX beam 2. With the blockage, the beam group 1may include Tx beam (3), and Rx beam (1), and the Tx beam group 2 mayinclude Tx beam {4,5} and Rx beam {4}.

The beam group may be affected by WTRU mobility. The WTRU in FIG. 6 maymove to a different location as shown in FIG. 8 . At the differentlocation in FIG. 8 , the TRP's Tx beam 3 and 4 may have similartransmission path(s) to the WTRU, and the TRP's Tx beam 3 and 4 may bereceived by WTRU's Rx beam 1. TRP's Tx beam 5 may be received by theWTRU's RX beam 4. With the WTRU mobility, the beam group 1 may includeTx beam {3,4}, and Rx beam {1}, and the Tx beam group 2 may include Txbeam {5} and Rx beam {4}.

The beam group may be affected by WTRU rotation. The WTRU in FIG. 6 mayrotate to a different orientation. At the different WTRU orientation,the TRP's Tx beam 3 and 4 may have similar transmission path(s) to theWTRU, and the TRP's Tx beam 3 and 4 may be received by WTRU's Rx beam 1.TRP's Tx beam 5 may be received by the WTRU's RX beam 4. With the WTRUrotation, the beam group 1 may include 1× beam {3.4}, and Rx beam {2},and the 1× beam group 2 may include 1× beam {5} and Rx beam {1}. In thecase of WTRU rotation, the Tx beams may not be adjusted in a beam group.

Processes and/or messages may be used for group-based beam operations.FIG. 10 shows an example for group-based beam formation, reporting andmaintenance. A TRP may use different beams for the TRP's serving area,and a WTRU may try to perform the beam sweeping and/or measurement. TheWTRU and TRP may exchange WTRU capability information, which may includethe beam capabilities, as described herein.

The WTRU may generate the beam group, for example, based on the WTRU'smeasurement. The beam group(s) may be summarized in a table. Take theexample in FIG. 6 , which is summarized in Table 2 below.

TABLE 2 Example of beam group formation (e.g., for the example in FIG.6) Group Id Component Tx beam Component Rx beam 1 2, 3 1 2 4, 5 4

The WTRU may send beam group formation to the TRP with the beam groupinformation as shown in TABLE 2. The TRP may confirm an beam groupformation indication. The beam group formation (e.g., TABLE 2) may besummarized and/or indicated in the example beam group IE as follows:

BeamgroupList = SEQUENCE (SIZE (1..maxGroupNum)) OF BeamgroupBeamgroup = SEQUENCE(  groupIndex INTEGER (1..maxGroupNum)  TXbeamList SEQUENCE(SIZE (1..maxTxBeamNum)) OF BeamId  RXbeamList  SEQUENCE(SIZE(1..maxRxBeamNum)) OF BeamId )where “BeamId” may indicate an index of the Tx/Rx beam, “maxTxBeamNum”may indicate the maximum number of Tx beams (e.g., 10 in FIG. 6 );“maxRxBeamNum” may indicate the maximum number of Rx beams (e.g., 4 inFIG. 6 ), “maxGroupNum” may indicate the maximum number of beam groups.

The WTRU may periodically measure the TX beams from the TRP. The WTRUmay report the WTRU's measurement in terms of RSRP, CSI, etc. torexample, as described herein. The measurement report may be based on abeam group(s) rather than on individual beam(s), for example, to reducesignalling overhead.

TABLE 3 Example of beam group reporting Group Id RSRP CSI 1 A1 Z1 2 A2Z2

The WTRU may send the group-based beam measurement report to the TRP,with the example information in TABLE 3. The group-based beam reporting(e.g., TABLE 3) could be summarized in the example beam group report IEas follows:

BeamgroupReportList = SEQUENCE (SIZE (1..maxGroupNum)) OFBeamgroupReport BeamgroupReport = SEQUENCE(  groupIndex  INTEGER(1..maxGroupNum)  rsrp  RSRP-Range  csi CSI-Range )

The WTRU may maintain a current beam group if there is no changes (e.g.,substantial changes) on the channels and/or environments. The WTRU naysend (e.g., periodically send) a beam group maintenance indicationmessage to the TRP, and the TRP may confirm the group maintenance to theWTRU.

In the case of WTRU mobility (e.g., as shown in FIG. 8 ), the beam groupinformation may be changed accordingly. With the beam measurementresults, the WTRU may send a beam group switch indication message to theTRP. The beam group switch indication message may contain a set ofupdated beam group information (e.g., as shown in TABLE 4). The beamgroup switch indication message may include a changed part of the beamgroup information. The beam group switch indication message may includea reason for the update (e.g., WTRU mobility), if the reason is known tothe WTRU.

TABLE 4 Example of beam group update for WTRU mobility Component TxComponent Rx Update reason Group Id beam beam (Optional) 1 3, 4 1 UEmobility 2 5 4

The TRP may update the TRP's local date base and/or send a confirmationto the WTRU, for example, once the TRP receives the beam group updateinformation.

The beam group update information (e.g., TABLE 4) may be summarized inan example beam group IE herein. The example beam group IE may include a(e.g., full) set of the updated beam group information. An extension maybe added to indicate the reason for the update. For example, “initial”may indicate the initial beam group formation, “UE mobility” mayindicate the update due to WTRU mobility, “blockage” may indicate theupdate due to blockage and “UE rotation” may indicate the update due toWTRU rotation, etc.

BeamgroupList = SEQUENCE (SIZE (1..maxGroupNum)) OF BeamgroupBeamgroup = SEQUENCE(  groupIndex  INTEGER (1..maxGroupNum)  TXbeamList  SEQUENCE(SIZE   (1..maxTxBeamNum)) OF BeamId  RXbeamList  SEQUENCE(SIZE   (1..maxRxBeamNum)) OF BeamId  Reason ENUMERATED(initial, UE mobility, blockage, UE rotation) OPTIONAL )

In the case of blockage (e.g., as shown in FIG. 7 ), the beam groupinformation may be changed accordingly. With the beam measurementresults, the WTRU may send a beam group switch indication message to theTRP. The beam group switch indication message may contain a (e.g., full)set of the updated beam group information (e.g., as shown in TABLE 5).The beam group switch indication message may include a changed part ofthe group information. The beam group switch indication message may addthe reason for the update (e.g., blockage) if the reason is known to aWTRU. The TRP may update the TRP's local data base and/or send aconfirmation to the WTRU, for example, once the TRP receives such beamgroup update information.

TABLE 5 Example of beam group update for blockage Component Tx ComponentRx Update reason Group Id beam beam (Optional) 1 3 1 Blockage 2 4, 5 4

In the case of WTRU rotation (e.g., as shown in FIG. 9 ), the beam groupinformation may be changed accordingly. With the beam measurementresults, the WTRU may send a beam group switch indication message to theTRP. This beam group switch indication message may contain a (e.g.,full) set of the updated beam group information (e.g., as shown in TABLE6). The beam group switch indication message may contain a changed partof the group information. The beam group switch indication message mayadd the reason for the update (e.g., WTRU rotation) if the reason isknown to the WTRU. The TRP may update the TRP's local data base and/orsend a confirmation to the WTRU, for example, once the TRP receives suchbeam group update information.

TABLE 6 Example of beam group update for UE rotation Component TxComponent Rx Update reason Group Id beam beam (Optional) 1 2, 3 2 UErotation 2 4, 5 1

FIG. 10 illustrates an example of a group-based beam operation between asingle TRP and a WTRU. As shown in FIG. 10 , the group-based beanoperation between the single TRP and the WTRU may include beam groupgeneration, group-based beam reporting, periodic beam group maintenance,and/or beam group switch due to WTRU mobility, blockage, and/or WTRUrotation. The TRP and the WTRU may exchange WTRU capability information.Beam sweeping and/or beam measurement may occur between the TRP and theWTRU. Beam group generation may include the WTRU sending a beam groupformation indication to the TRP and/or the TRP sending a beam groupformation confirmation to the WTRU. The group-based beam reporting mayinclude beam sweeping and/or beam measurement between the TRP and theWTRU, and the WTRU sending the group-based beam measurement reporting tothe TRP. The periodic beam group maintenance may include the WTRUsending a beam group maintenance indication to the TRP and the TRPsending a beam group maintenance confirmation to the WTRU. The beamgroup switch due to WTRU mobility may include a WTRU mobility, beamsweeping and/or beam measurement, the WTRU sending a beam group switchindication to the TRP, and/or the TRP sending a beam group switchconfirmation to the WTRU. The beam group switch due to blockage mayinclude a blockage, beam sweeping and/or beam measurement, the WTRUsending a beam group switch indication to the TRP, and/of the TRPsending a beam group switch confirmation to the WTRU. The beam groupswitch due to WTRU rotation may include a WTRU rotation, beam sweepingand/or beam measurement, the WTRU sending a beam group switch indicationb the TRP, and/or the TRP sending a beam group switch confirmation tothe WTRU.

The example in FIG. 10 may be extended to multiple TRPs. FIG. 11 showsan example of group-based beam operations over two TRPs, where the TRPsare not transparent to the WTRU. As shown in FIG. 11 , the group-basedbeam operation between fie two TRPs and the WTRU may include beam groupgeneration, group-based beam reporting, periodic beam group maintenance,and/or beam group switch due to WTRU mobility, blockage, and/or WTRUrotation. The TRPs and the WTRU may exchange WTRU capabilityinformation. Beam sweeping and/or beam measurement may occur between theTRPs and the WTRU. Beam group generation may include the WTRU sendingbeam group formation indications to the TRPs and/or the TRPs sendingbeam group formation confirmations to the WTRU. The group-based beamreporting may include beam sweeping and/or beam measurement between theTRPs and the WTRU, and the WTRU sending the group-based beam measurementreporting to the TRPs. The periodic beam group maintenance may includethe WTRU sending beam group maintenance indications to the TRPs and theTRPs sending beam group maintenance confirmations to the WTRU. The beamgroup switch due to WTRU mobility may include a WTRU mobility, beamsweeping and/or beam measurement, the WTRU sending beam group switchindications to the TRPs, and/or the TRPs sending a beam group switchconfirmations to the WTRU. The beam group switch due to blockage mayinclude a blockage, beam sweeping and/or beam measurement, the WTRUsending beam group switch indications to the TRPs, and/or the TRPssending beam group switch confirmations to the WTRU. The beam groupswitch due to WTRU rotation may include a WTRU rotation, beam sweepingand/or beam measurement, the WTRU sending beam group switch indicationsto the TRPs, and/or the TRPs sending beam group switch confirmations tothe WTRU.

Techniques for explicit group-based beam indication may be provided. Agroup-based beam indication(s) may be (e.g., explicitly) signalled to aWTRU via RRC signalling, L2 or L1 signalling such as MAC CE areNR-(e)PDCCH/NR-DCI, or RAR grant. The group-based beam indication(s) mayinclude one or a (e.g., any) combination of the following: A TRP gNB mayindicate a beam group to facilitate the WTRU's data reception; the TRPor gNB may indicate intra-group or inter-group beam measurement for beamtracking, transmission, and/or switching (e.g., intra-group beamswitching may or may not be singled between the TRP/gNB and the WTRU.Inter-group seam group switching may be informed between the TRP/gNB andthe WTRU); the TRP/gNB may indicate the number of beam groups to bemeasured and/or reported by the WTRU; the TRP/gNB may indicate whichbeam group to be measured and/or reported by the WTRU; the TRP/gNB mayindicate what type of beam measurement information (BMI) or beam relatedinformation (BRI) to be reported by the WTRU; and/or group-based beamreport may be done in a periodic or aperiodic manner, e.g., configuredby the TRP or gNB (e.g., the TRP/gNB may indicate a type of periodicNR-PUCCH feedback. The TRP/gNB may indicate time/frequency resource(s)for a aperiodic report).

A group-based beam indication(s) (e.g., one or more of the indicationsherein) may be explicitly signalled, or implicitly signalled if theTRP/gNB does not know (e.g., not exactly know) the WTRU's measurementcapability. For example, a threshold for the associated or correspondingBMI or BRI (e.g., instead of explicitly signaling an exact number ofbeam groups to be measured and reported by the WTRU) may be signalled tothe WTRU. The WTRU may automatically or implicitly determine the numberof beam groups to be reported to the TRP/gNB. In an exampleimplementation, the TRP/gNB may signal a reporting threshold andassociated BMI. When the beam group's measurement is above the reportingthreshold, the corresponding beam group's BMI will be reported. In anexample implementation, the TRP/gNB may signal a non-reporting thresholdand associated BMI. When the beam group's measurement is below thenon-reporting threshold, the corresponding beam group's BMI will not bereported. In an example implementation, the TRP/gNB may signal areporting threshold and associated BMI, and a minimum number of beamgroups to be reported. When a total number of the beam groups whosemeasurement is above the reporting threshold is less than the explicitlysignalled minimum number of beam group, the WTRU may report at leastsignalled/required minimum of beam groups information.

Techniques for implicit group-based beam indication may be provided. Agroup-based beam indication(s) may be implicitly signalled to the WTRU,for example, based on preset rules as described herein. FIG. 12 shows anexample of a multi-beam transmission system where different WTRUs aregrouped under a similar beam(s). As shown in FIG. 12 , WTRUs 1202, 1204,and 1206 may be grouped under beam 1212 (e.g., in beam group 1). WTRUs1208 and 1210 may be grouped under beam 1214 (e.g., in beam group 2). Ina multi-beam transmission system, a beam may be carrying independentinformation intended for a specific group of receive units. A receiveunit(s) may determine an identity(s) of a (e.g., each) transmitted beamand/or implement a receive beamforming for a selected or desired DLtransmitted beam. For example, for proper demodulation and interferencemanagement, a receive unit(s) may determine an identity(s) of a (e.g.,each) transmitted beam and/or implement an accurate receive beamformingfor the selected or desired DL transmitted beam.

The receive unit may be enabled to identify the desired beam, forexample, based on a transmission of an identifier. The identifier may beunique. The transmitter unit may embed the identifier per transmittedbeam to assist identification of the desired beam by the receive unit.The identifier may be selected from a pool of the orthogonal orsemi-orthogonal signals (e.g., signals that are already known to bothtransmit and receive units). For example, a unique identifier signal maybe implemented in a number of different ways including one or more oftransmission of a sequence, usage pattern of specific resources, orthrough a feature or property of the waveform. A single identifier or acombination of multiple identifiers may be used.

The receive unit may be enabled to identify the desired beam based ondetection of a transmitted sequence(s). A sequence(s) with goodcorrelation properties may be transmitted on a dedicated resource(s).For example, a ZC sequence that is defined with different lengths may beused. A longer sequence may be used when a higher reliability for beamseparation is used (e.g. required). As shown in FIG. 13 , the sequencemay be mapped on a numbs of resources that span over the frequency andthe time and/or transmitted in a periodic or a-periodic manner. Thesequence may be beamformed by the same beamformer as used for otherchannel(s).

The location of the dedicated resources may be fixed (e.g., alwaysfixed) or configured. In a DL scenario, information about a location ofan identifier signal may be available, for example, semi-statically orthrough initial RRC signalling.

For a (e.g., each) beam-group, resources considered for transmission ofthe identifier sequence(s) may have the same configuration as otherbeams and/or may be configured independent of others. The configurationinformation may include, one or more of, but not limited to, size(s) ofthe resources, as different beams may be configured with sequences ofdifferent length, resource location definition(s) of the resources intime/frequency grid, and/or frame and/or subframe periodicity and timeoff-set of transmission(s) of the identifier sequence(s).

Beam-group identification may be performed through a usage pattern ofspecific resources. Some of resources may be used in a specific mannerto indicate an identity(s) of a beam-group(s). For example, a finite setof resources that are used for data transmission may be punctured with aspecific pattern to indicate the identity(s) of the beam-group(s). FIG.14 shows an exemplary implementation where a finite set of the resourcesthat were originally considered for another channel, e.g., shared data,may be punctured according to the beam identity(s). Data may beeffectively punctured or rate-matched around a punctured location. Itmay be assumed that a WTRU is aware of a general location of theidentification resources. The WTRU may perform hypothesis testing toidentify the punctured/null location(s) to determine an employedpuncturing pattern representing the beam-group identification and/ordemodulate the transmitted data.

The location(s) of dedicated resources may be fixed (e.g., always fixed)or configured. In a DL scenario, information about the location(s) ofthe set of resources used for puncturing may be available, for example,semi-statically or through initial RRC signalling.

For a given beam-group, a resource blocks) considered for puncturing mayhave the same configuration as other beams and/or may be configuredindependent of others. The configuration information may include one ormore of, but not limited to, a size(s) of the set of resources forpuncturing, as different beams may be configured with different blocksizes, resource location definition(s) of the block(s) considered forpuncturing in a time/frequency grid, and/or frame and/or subframeperiodicity and time off-set of transmission of the block(s) forpuncturing.

Beam-group identification may be based on a specific use of pattern. Abeam may be configured with a different set of RS patterns. Thedifference in a (e.g., each) pattern may be reflected in the location,the density, and/or distribution of RS's across a subframe. The numberof potential patterns may be limited and/or may be known to WTRUs. AWTRU may begin demodulation by hypothesis testing of a differentpattern(s) to determine the beam identity and/or perform otherdemodulation-related processing.

Beam-group identification may be carried out by examining a feature or aproperty of an employed waveform. An example of such property mayinclude a word (e.g., a unique word) that may be carried by a waveform.As demonstrated in FIG. 15 a unique word may be defined in a frequencyor the time domain. A unique word may be already in use for otherreceiver purposes such as synchronization or channel tracking. Thechoice of the unique word may be different per beam to allow beamidentification. In an example where the unique word is based on a ZCsequence, a choice of parameters such as cyclic shift, root sequence maybe used to carry beam identification. The transmission of the uniqueword for beam identification may be kept at a symbol level oral a lowerrate. For example, the identification may be carried by a single uniqueword or based on multiple different unique words spread over severalsymbols.

The location of the transmitted unique word may be fixed (e.g., alwaysfixed) or configured. In a DL scenario, the information about a locationof the unique word may be available, for example, semi-statically orthrough initial RRC signalling.

For a (e.g., each) beam-group, the location of the unique word may havethe same configuration as other beams or may be configured independentof others. The configuration information may include: size of the uniqueword, as different beams may be configured with different unique wordlength, the multitude of unique wards used for the beam identification,resource location definition of the unique word in a lime/frequencygrid, and/or frame, subframe and/or symbol periodicity and time off-setof transmission(s) of the block(s) for puncturing. FIG. 16 shows ageneral procedure of a beam-group identification process. For example,at 1602, the WTRU may be configured with the basic parameters related tothe beam identification mechanism, e.g., resource location, size,timing, pool of the potential secondary parameters such as ZC cyclicshift, etc. At 1604, the WTRU may extract the resources related to thebeam identification. At 1606, the WTRU may perform hypothesis testing todetermine the identity of the transmitted beams. At 1608, the WTRU mayadjust the WTRU's receive beamforming, for example, according to adirection of a transmitted DL beam carrying the desired identity.

Based on reception of beam group information (e.g., beam groupinginformation), the WTRU may measure beam related information (e.g.,execute the beam related information measurement). The WTRU may reportthe measured beam related information back to the TRP, for example, viagroup-based reporting. Group-based beam reporting (e.g., group-basedreporting) may include reporting one or more of the following beammeasurement information (BMI) or beam related information (BRI):reference signal received power (RSRP), reference signal receivedquality (RSRQ), channel state information (CSI), beam index, beam groupindex, channel quality indicator (CQI), RI, and CSI resource index (CRI)associated with beam information. The one or more of the BMI or BRI maybe included in a group-based report. The one or more of the BMI or BRIto be reported by the WTRU may be pre-specified, configured by a RRCmessage, or dynamically signalled by L1/L2 signalling such as MAC CE orNR-(e)PDCCH/NR-DCI. The WTRU may report BMI or BRI in a periodic oraperiodic manner, for example, as configured by a TRP or a gNB.Event-based or aperiodic beam reporting may be triggered by the networkor the WTRU(s). For example, one or more new beam candidates may bedetected to have better beam quality than the serving beam and/orreported by the WTRU. RSRP, RSRQ may be interchangeably used as L1-RSRPand L1-RSRQ respectively.

Group-based beam reporting may reduce the amount of WTRU reporting(e.g., on BRI), for example, by reducing overhead associated with thereporting, Group-based beam reporting may be performed in one or anycombination of the following approaches.

For example in an approach for group-based beam reporting, the WTRU mayreport the best BRI (e.g., largest L1-RSRP) for a component beam in abeam group. In an example, some or all beams may be grouped into a totalnumber of beam groups (e.g., N). The WTRU may report the best RSRP/CSIfor a component beam in each of M beam groups and the associated beamindex for the component beam in each of the M beam groups (e.g.,M<=total number of beam groups N). M and/or N may be pre-configured,semi-dynamically signalled, and/or or dynamically signalled. Forexample, M and/or N may be determined based on one or more of thefollowing. M and/or N may be configured by the network. M and/or N maybe determined based on WTRU capability such as the number of beams theWTRU can simultaneously receive. M and N may be selected by the WTRU.

The WTRU may report the J best BRI (e.g., top J BRI or largest JL1-RSRP) for J component beams in a beam group, where J>=1. The WTRU mayreport associated beam IDs in a pre-specified or configured orderingaccording to J best RSRP/CQI values (e.g., J best or largest L1-RSRPand/or J best wideband CQI values). For example, the pre-specified orconfigured ordering may be in a ascending or descending order accordingto the RSRP and/or CQI values).

In an approach for group-based beam reporting, the WTRU may report theaverage or mean or medium BRI for a component beam in a beam group. Forexample, some or all beams may be grouped into a total number of beamgroups (e.g., N). The WTRU may report the average or mean or mediumRSRP/CSI for a component beam. The WTRU may report the associated beamindex of the component beam. In an example, the WTRU may report theaverage or mean or medium RSRP/CSI for a component beam in each of Mbeam groups (M<=total number of beam groups N) and the associated beamindex of the component beam in each of M beam groups. M and N may beconfigured by network via RRC messaging or dynamically signalled inNR-(e)PDCC-I/NR-DCI field. For example, N may be configured based onWTRU capability, M may be dynamically signalled in NR-DCI forgroup-based beam reporting. In some instances, M may be the same foreach beam reporting. In some instances, M may be different for each beamreporting.

In an approach for group-based beam reporting, the WTRU may report BRIfor a reference or representative beam, for example, the average BRI fora beam group, and a differential BRI(s) for the rest beam(s) within thesame beam group. The differential BRI may be pre-defined, specified, orconfigured in a certain quantization level. The quantization level maybe referred to as the differential beam reporting resolution. Thereported BRI may include RSRP, The reference BRI may include thereference RSRP, which may include one or more of the max RSRP, thelargest RSRP, the best RSRP, the worst RSRP, the average RSRP or themedium RSRP of a reported beam group. The differential RSRP may indicatethe RSRP of an (e.g., each) individual beam within the same beam groupwith respect to the reference RSRP. The reference RSRP may be reportedby the WTRU and/or may be determined or configured by the TRP based on arule. The rule may be pre-defined or specified or configured orsignalled. For different reference RSRP, same or different differentialbeam reporting resolutions (e.g., or stepping size of differentialquantization) may be used, for example, based on a trade-off betweensignalling overhead and reporting accuracy for beam management. Forexample, to reduce signalling overhead, a large quantization level or alow resolution may be used. A small quantization level or highresolution may be used if accurate beam reporting is desired. Thedifferential beam reporting resolution may be specified, configured(e.g., via RRC message or signalled in DCI). The differential beamreporting resolution may be determined by the WTRU and/or reported inbeam reporting.

The differential beam reporting per beam group may be extended to someor all beam groups. For example, the reference RSRP may be selected asone of the max RSRP, the largest RSRP, the best RSRP, the worst RSRP,the average RSRP or the medium RSRP of some or all reported beam groups.The differential RSRP may indicate the RSRP of an (e.g., each)individual beam for the reported beam groups with respect to thereference RSRP defined for the reported beam groups. The reference RSRPmay be reported once for some or all reported beam groups as commonbeam-group reporting (e.g., to further reduce the signalling overhead).The reported beam groups may be associated via the common beam-groupreporting. The reference RSRP may be reported on a per beam group basis.The reference RSRP may be a specified default value or configured bygNB. Bit-width for the reference RSRP and the differential RSRP may bepre-specified or configured as the same or different values. Forbeam-group based different beam reporting, the reference L1-RSRP may bereported with the same bit-width for different beam groups, while thedifferential L1-RSRP may be reported with same or different bit-widthfor different beam groups which may depend on the number of beams fordifferent beam groups if different stepping size of differentialquantization is used for different beam groups. When the number of beamgroup is equal or configured to 1, beam-group based differential beamreporting above may be used for non-beam-group differential beamreporting for multiple beams (e.g. N2 beams within 1 beam group): thereference L1-RSRP may be reported with a first bit-width (e.g., X1bits=7 bits), and the differential L1-RSRP may be reported with a secondbit-width (e.g., X2 bits=4 bits).

For example, a beam group may include 12 beams (e.g., narrow beams). Thereference RSRP may be the average RSRP/CQI of the beam group. Thereference RSRP may be the average RSRP/CQI over the 12 beams. Beam ID(s)for the beam(s) whose RSRP/CQI is closest to the average RSRP/CQI, andthe differential RSRP/CQI with respect to the reference RSRP (e.g., theaverage RSRP/CQI) may be reported using various techniques.

With an example, the total number of beams with a beam group may be T.The number of sub-groups within the beam group may be integer(T/B_delta) which denotes as L. L may be configured or dynamicallysignalled from gNB/TRP depending on a signalling overheadrequirement(s). B_delta may denote the quantization level of asub-group(s) with the beam group. In this example, T=12 beams. B_delta=4beams, then L=12/4=3 sub-groups. The group-based beam report may includethe average RSRP/CQI and beam ID(s) associated with beam(s) which hasthe closest RSRP/COI value(s) to the average RSRP/CQI. The group-basedbeam report may include an average RSRP/CQI(s) for 3 sub-groups andpotentially associated sub-group beam ID(s).

With an example technique, the differential RSRP/CQIs with regards tothe reference RSRP/CQI for a certain number of beams within a beam groupmay be reported. The group-based beam report may include the averageRSRP/CQI value and the associated beam ID for the beam which has theclosest RSRP/CQI value to the average RSRP/CQI. The group-based beamreport may include differential RSRP/CQI(s) with regards to the averageRSRP/CQI for a certain number (e.g., 6) beams and beam a associated withthe beams (e.g., the 6 beams). The differential RSRP/CQIs and/or thebeam IDs may be reported in a prespecified or configured order, forexample, an ascending or descending order in terms of differentialRSRP/CQI values.

With an example technique, the differential RSRP/CQI with regards to thereference RSRP/CQI for one or more beams (e.g., each beam) within a beamgroup may be reported. The group-based beam report may include theaverage RSRP/CQI and a beam ID(s) associated with a beam(s) that mayhave the closest RSRP/CQI value to the average RSRP/CQI. The group-basedbeam report may include a number of differential RSRP/CQI(s) for the oneor more beams (e.g., each beam) and beam IDs associated with the one ormore beams (e.g., each beam or 12 beams in this example). Thedifferential RSRP/CQIs and/or the beam IDs may be reported in aprespecified or configured order, for example, an ascending ordescending order in terms of differential RSRP/CQI values.

The differential beam reporting techniques described herein may be usedfor per-beam based reporting over time. For example, the reference RSRPmay be a RSRP reported at a time (for example, at the first time whenRSRP is reported), and the differential RSRP may be the RSRP reported ata later time with respect to the reference RSRP (e.g., at the secondtime).

In an approach for group-based beam reporting, the WTRU may dynamicallyreport BRI for beams (e.g., all beams) in K of M beam groups (M<=totalnumber of beam groups N) and the best BRI in (M-K) of M beam groups(M<=total number of beam groups N). K may be dynamically indicated orsignalled to the WTRU by DCI. For example, when the number of beams foreach group, denoted as N_(m), is configured to be 1, this approach forgroup-based beam reporting may become per-beam basis reporting (e.g.,beam-based reporting, wherein group-based reporting turns off).

In an approach for group-based beam reporting, the WTRU may beconfigured to report BRI for all beams for each of M beam groups. Thisapproach for group-based beam reporting may be associated with per-beambasis reporting. This approach for group-based beam reporting may beused during the initialization of beam acquisition of TRP Tx beam/WTRURx beam. This approach for group-based beam reporting may beaperiodically triggered by network or the WTRU. This approach forgroup-based beam reporting may be configured in a periodical manner, forexample, with long periodicity to maintain the beam group or keep thebeam group updated and tracked accurately.

In an approach for group-based beam reporting, the WTRU may report theworst BRI for a component beam(s) in a beam group. For example, the WTRUmay report the best RSRP/CSI for a component beam(s) and a beam indexassociated with the component beam(s) in each of M beam groups (M<=totalnumber of beam groups N). M and/or N may be configured or dynamicallysignalled in an NR-(e)PDCCH/NR-DCI field.

The measurement and reporting approaches discussed herein may beapplicable to Quasi Co-located (QCL) beams at the TRP or Quasi co-Beam(QCB) beams at a WTRU (e.g., any of the WTRUs).

Reduced group-based beam report may be periodic or triggeredaperiodically by network or a WTRU. The WTRU may send group-based beamreporting via UL channels such as NR-PUCCH or NR-PUSCH. If a largeamount of group-based reporting is performed (e.g., beam-based full WTRUreport), the group-based reporting may be carried over NR-PUSCH. Dataand group-based beam report may be multiplexed. Data and group-basedbeam report may be joint-coded. Reduced amount of group-based WTRUreport (e.g., a reduced level of reporting compared to a level ofreporting associated with beam-based reporting) may be carried viaNR-PUCCH. Various types of periodic NR-PUCCH feedback for BRI may beprovided using any of the group-based beam reporting methods describedheroin.

A beam group may be defined by the TRP or the WTRU. A beam group may bedefined based on QCL or QCB beams. A beam group may elect arepresentative beam or beam-pair (e.g., an anchor beam/beam-pair) onwhich measurement and/or reporting may be performed. A beam-measurementreference signal (BRS) may be transmitted on the representativebeam(s)/beam-pair(s). Initial access signals and procedures such assynchronization, system information acquisition using the NR-PBCH andNR-RACH may occur on the representative beam(s)/beam-pair(s). Theapproaches used for group-based reporting and/or beam-based reportingdiscussed herein may be used. For example, the approach for group-basedbeam reporting where the WTRU reports BRI for a reference orrepresentative beam and a differential BRI(s) far the rest beam(s)within the sane beam group may be used. Additional differentialinformation compared to the representative beam/beam-pair(s) may betransmitted.

The representative beam or beam-pair(s) may be selected using one ormore of the following approaches.

In an approach for selecting the representative beam or beam-pair(s), a(e.g., one) beam/beam-pair(s) may be selected as the representativebeam/beam-pair(s). This beam/beam-pair may be statically,semi-statically, or dynamically selected. This beam/beam-pair may bestandard specified (e.g., pre-specified or pre-configured). For example,the representative beam or beam-pair(s) may be specified as thebeam/beam-pair with a BMI/BRI element (e.g., value) closest to themean/median/mode of the BMI/BRI elements (e.g., all of the BMI/BRIelements) of the beam/beam-pair(s).

In an approach for selecting the representative beam or beam-pair(s),the beam/beam-pair(s) in the beam group (e.g., all beam/beam-pair(s) inthe team group) may be eligible to be selected as the representativebeam/beam-pair(s). The specific beam/beam-pair(s) may be selected basedon one or more pre-defined rules. For example, random selection and/orcyclic selection (e.g., as used as pre-defined rules) may be performed.

In an approach for selecting the representative beam or beam-pair(s),for example, a transmit beam (e.g., one or all transmit beams) may beselected as the representative transmit beam with measurements providedon the receive beams. In some instances, only the transmit beams may beselected as the representative transmit beam with measurements providedon all of the receive beams. In an example, one or more of the followingmay be performed. A (e.g., one) beam may be selected as therepresentative beam. A receiver that has more than one receive beam maythen send the measurements for some (e.g., all) the receive beams forthat representative beam. If the receiver is able to form the receivebeams (e.g., at the same time), then it may measure on some (e.g., all)the receive beams and/or send the feedback. If the receiver is able toform the receive beams (e.g., one at a time), then the receiver may feedback (e.g., only feed back) the current beam. The transmitter may send(e.g., have to send) a measurement signal on the transmit beam multipletimes.

In an example, if the transmitter is able to form multiple transmitbeams (e.g., at the same time), it may do this simultaneously.Measurement signals nay (e.g., have to) be orthogonal or separable fromeach beam. For example, it may form a beam on each polarization and/orsend the information simultaneously.

This approach for selecting the representative beam or beam-pair(s) maybe performed simultaneously it the WTRU is capable of forming multiplereceive beams simultaneously. This approach for selecting therepresentative beam or beam-pair(s) may be performed sequentially if theWTRU is not capable of forming the multiple receive beamssimultaneously. FIG. 17 depicts an example beam group withrepresentative beam(s). As shown in FIG. 17 , the beam group may includebeam 1702, beam 1704, and beam 1706. Beam 1702 may be selected as therepresentative beam. FIG. 18 depicts an example beam-pair group withrepresentative beam-pair(s). As shown in FIG. 18 , the beam group mayinclude beam pair 1802, beam pair 1804, and beam pair 1806. Beam pair1802 may be selected as the representative beam pair.

In an approach for selecting the representative beam or beam-pair(s), acomposite beam/beam-pair representative of the beam/beam-pairs in a beamgroup may serve as the representative beam/beam-pair. An exemplarycomposite representative beam is illustrated in FIG. 19 . As shown inFIG. 19 , the beam group may include beam 1904, beam 1906, aid beam1908. A composite beam 1902 may be selected as the representative beam.For example, the composite beam 1902 may include beams 1904-1908. Asshown in FIG. 19 , the composite beam 1902 may have a wider beam widththan the beams in the beam group such as beam 1904. In one example, thecomposite/representative beam may be a beam that has a beamwidth thatspans the union of the beam widths of the beams it represents. In oneexample, the composite/representative beam may be a beam that spans allthe WTRUs that may be connected to the beams it represents. The widerbeam width may result in beamforming gain for power measurements such asSINR and CQI. The change/difference in beamforming gain for powermeasurements such as SINR and CQI due to the wider beam width of therepresentative beam may be compensated for. For example, as thebeamwidth increases, the gain of a resulting sector may be different(e.g., less than) the gains of the beams it represents. As such, ifmeasurements are made based on the wider beam, some transformation onthe estimated metrics that are measured may (e.g., have to) beperformed.

In an approach for selecting the representative beam or beam-pair(s), ameasurement beam group may be defined separately from a transmissionbeam-pair group. As an example, a measurement beam group may be definedas including a specific set of transmit beams or receive beams. Atransmission beam-pair group may include (e.g., be specified to include)a set of transmit-receive beam pairs. Translation between themeasurement beam group and the transmission beam-pair groups may beperformed in various ways. In a translation, measurements (e.g., anymeasurements) made on the measurement beam group may be (e.g., have tobe: modified/translated/processed to make them applicable to thetransmission beam group. For example, difference between the gains ofthe two sets of beams may be looked at and/or changes may be made basedon the difference.

may A distinction (e.g., the separate definition for the measurementbeam group and the transmission beam-pair group) is illustrated in FIGS.20 and 21 . FIG. 20 depicts an example of a transmission beam-pairgroup(s). FIG. 21 depicts an example of a measurement beam group(s). Asshown in FIG. 20 , a transmission beam-pair group may be define. Thetransmission beam-pair group may include transmission beam-pair 2002,transmission beam-pair 2004, and transmission beam-pair 2006.Transmission beam-pair 2002 may be selected as the representativetransmission beam-pair. A beam-pair may include a pair of transmit andreceive beams. As shown in FIG. 21 , measurement beam groups may bedefined separately from the transmission beam-pair group in FIG. 20 .The measurement beam group 2102 may include beam RX 2106, beam 2108, andbeam 2110. Beam 2106 may be the representative beam of the measurementbeam group 2102. The measurement beam group 2104 may include beam 2112beam 2114, and beam 2116. TX beam 2112 may be the representative beam ofthe measurement beam group 2104.

Some elements (e.g. RI) of the BMI/BRI may be same for thebeam/beam-pair(s) in a beam-group, while some elements (e.g. the SINR)of the EMI/BRI may differ for different beam/beam-pair(s) in the group.A process may be initiated in which the different elements of theBMI/BRI for the constituent beam/beam-pairs(s) may be calibratedaccording to an BMI/BRI element of the representative beam/beam-pair(s).The calibration may facilitate (e.g., enable) an estimation of a BMI/BRIelement value (e.g., the correct BMI/BRI element value), for example,based on a reported value for the BMI/BRI element of the representativebeam/beam-pairs(s). For example, if the beam group measurement reports avalue of X, then beam 1's measurement may be X+b1, beam 2's measurementmay be X+b2, etc where b1, b2 etc may be the calibrated values.

The process may be used when the members (e.g., the constituentbeam/beam-pairs(s)) of the beam group have different beam-widths. Theprocess may be used when the members of the beam group may be directedon channel clusters that suffer from attenuation (e.g., greater/lessattenuation). As an example, the WTRU or gNB may identify therepresentative beam/beam-pair(s), and a receiving node (e.g., the WTRUor gNB) may feed back/feed forward intonation relative to therepresentative beam/beam-pair(s) (e.g., differential SINR or COI).

RSRP (e.g., L1-RSRP) reporting may be implemented for multiple beams. AWTRU may measure and/or report one or more measurement results for oneor more downlink signals. For example, the WTRU may be configured,indicated, and/or triggered to measure and/or report the measurementresults. A (e.g., each) downlink signal may be associated with a beam.The measurement results may be one (e.g., at least one) or more of achannel quality indicator (CQI), a reference signal received power(RSRP), or a beam reference signal indicator.

RSRP may be categorized to one or more types and used in one or more ofthe following ways. In an example, a first type RSRP may be used if theRSRP is measured in a first time window (e.g., a time window configuredor used in a higher layer such as a sliding time window) and a secondtype RSRP may be used if the RSRP is measured in a second time window(e.g., a time window configured or used in a physical layer). In anexample, a first type RSRP may be used if the RSRP is measured in a timewindow, while the second type RSRP may be used if the RSRP is measuredat a time instance where the measurement reference signal istransmitted. In an example, a first type RSRP may be associated with atime window that may be configured or determined via higher layer, and asecond type RSRP may be associated with a time window that may beconfigured or determined via L1 signalling (e.g., DCI). In an example,the first type RSRP may be referred to as _3-RSRP and the second typeRSRP may be referred to as L1-RSR.

In an example, the measurement results may include a beam referencesignal indicator. For example, one or more beam reference signals may beconfigured or used, and a WTRU may report a preferred beam referencesignal index.

A WTRU may be configured, indicated, and/or triggered to report one ormore measurement results (e.g., L1-RSRP). A (e.g., each) measurementresult may be associated with a beam reference signal. A beam referencesignal as used herein may be used interchangeably with channel stateinformation reference signal (CSI-RS), demodulation reference signal(DM-RS), phase tracking reference (PTRS), synchronization signal block(SS block), and SS/PBCH block. One or more of following may apply.

A WTRU may be configured with the number of beams and/or the number ofmeasurement results for the reporting. For example, a WTRU may beindicated via higher layer signalling, L1 signalling (e.g., DCI) for thereporting of one or more measurement results. A DCI that is used foraperiodic CSI reporting triggering may be used to indicate the number ofbeams to report, wherein beams may be interchangeably used with themeasurement results reference signals, RSRP, COI, or L1-RSRP.

One or more RNTI may be used to indicate the number of beams to reportwhen a WTRU is triggered, for example, via aperiodic CSI reporting ofsemi persistent CSI reporting with a DCI. A first RNTI may be used tomask the CRC of the associated DCI if the number of beams to report isN1. A second RNTI may be used to mask the CRC of the associated DCI ifthe number of beams to report is N2. For example, N1 may be a fixed orpredefined number (e.g., N1=1), and N2 may be a number configured viahigher layer signalling (e.g., N2>1)).

A WTRU may be configured, indicated, and/or triggered to report a singlebeam among a plurality of beams. The WTRU may determine the single beamto report based on one or more of following: a WTRU may determine a beam(e.g., a beam reference signal) which has a highest RSRP value. Forexample, a WTRU may measure RSRP on one or more beams, compare themeasured RSRP values, and determine the beam with a highest measuredRSRF value(s). The WTRU may report the beam index (e.g., a beamreference signal index) and the measurement value (e.g., L1-RSRP)associated with the beam index. The beam that the WTRU selected ordetermined for single beam reporting may be referred to as one or moreof a preferred beam, a preferred beam reference signal, a selected beam,or a selected beam reference signal.

A WTRU may be configured, indicated, and/or triggered to report morethan one beam within a plurality of beams using various approaches. Oneor more of following may apply: a WTRU may report N2 beams: and/or aWTRU may report N2 beams and the bit-width for each beam measurementvalue.

In an approach for reporting more than one beam within a plurality ofbeams, a WTRU may report N2 beams (e.g., N2 beam IDs and N2 beammeasurement values such as N2 RSRP or N2 L1-RSRP) in one reportinginstance, wherein N2>1 and N2 is no more than the maximal number ofconfigured Tx beams to be reported in one reporting instance (e.g.,N_max). N_max may be less than the maximal number of configured Tx beamsfor beam measurement. N2 beam measurement values may be reported via anuplink control channel (e.g., an individual uplink control channel). Forexample, a WTRU may be configured with N2 physical control uplinkchannel (PUCCH) resources. One or more of the PUCCH resources (e.g.,each PUCCH resource) may be used to report a beam measurement value. Theone or more uplink control channels for reporting of N2 bean measurementvalues may be multiplexed in time. For example, N2 consecutive PUCCHresources in lime may be used for reporting N2 beam measurement values.A transmission order (e.g., of the N2 consecutive PUCCH resources) maybe based on the measurement values. For example, the PUCCH resource(s)associated with the highest measurement value may be transmitted firstand the PUCCH resource(s) associated with the other measurement valuesaccording to the other measurement values. The PUCCH resource(s)associated with the lowest measurement value may be transmitted firstand the PUCCH resource(s) associated with the other measurement valuesaccording to the other measurement values. N2 beam measurement valuesmay be reported via a physical uplink shared data channel (PUSCH), andthe N2 beam measurement values may be jointly coded or separately coded.

In an approach for reporting more than one beam within a plurality ofbeams, a WTRU may report N2 beams or beam IDs, and the bit-width for a(e.g., each) beam measurement value. The bit-width for a (e.g., each)beam measurement value may be determined based on one (e.g., at leastone) or more of the following. The bit-width for a (e.g., each) beammeasurement value may be determined based on uplink channel used for N2beam reporting. For example, a first bit-width (e.g., X1 bits) may beused for reporting N2 measurement values if a first uplink channel(e.g., PUSCH) is used. A second bit-width (e.g., X2 bits) may be usedfor reporting N2 measurement values if a second uplink channel (e.g.,PUCCH) is used.

The bit-width for a (e.g., each) beam measurement value may bedetermined based on TTI length of the uplink channel used for N2 beamreporting. For example, a first bit-width (e.g., X1 bits) may be used ifa first TTI length (e.g., 1 ms) is used for the associated orcorresponding uplink channel. A second bit-width (e.g., X2 bits) may beused if a second TTI length (e.g., 0.5 ms) is used (or the associated orcorresponding uplink channel. The TTI length may be determined based onnumerology (e.g., subcarrier spacing) and/or the number of symbols usedfor a TTI.

The bit-width for a (e.g., each) beam measurement value may bedetermined based on the number of beams. For example, if N2 is greaterthan a predefined threshold, a first bit-width (e.g., X1 bits) may beused. If N2 is less than or equal to a predefined threshold, a secondbit-width (e.g., X2 bits) may be used.

The bit-width for a (e.g., each) beam measurement value may bedetermined based on most significant bits (MSB) or least significantbits (LSB). For example, when X1>X2, the X2 bits may be most significantbits (MSB) of X1 or least significant bits (LSB) of X1, or vice versa:Xi may be the MSB or the LSB.

The bit-width fora (e.g., each) beam measurement value may be determinedbased on an explicit indication. The explicit indication may betransmitted or received via a higher layer signalling or a L1 signalling(e.g., DCI). For example, when L1 signalling is used, the L1 signallingthat indicates or triggers N2 beam reporting may include the bit-widthinformation.

In an approach for reporting more than one beam within a plurality ofbeams, a WTRU may report N2 beams, and the bit-width for a (e.g., each)beam measurement value. The bit-width for a (e.g., each) beammeasurement value may be determined based on one (e.g., at least one) ormore of following. The first beam which may be a highest measurementvalue may be reported with a first bit-width (e.g., X1 bits). Themeasurement value of the first beam may be reported in an uplink channelor uplink resource that is associated with higher reliability than otheruplink channels) or uplink resource(s). For example, if PUCCH and PUSCHare used, the measurement value of the first beam may be reported inPUCCH while the rest of measurement values may be reported in PUSCH. Inanother example, the measurement value of the first beam may be reportedin the uplink resources which may be closer to a reference signallocation (e.g., symbol next to the reference signal symbol. The secondbeam or the rest of beams may be reported with a second bit-width (e.g.,X2 bits). In case of reporting differential L1-RSRP for multiple beams(e.g. N2 beams), the reference L1-RSRP may be reported with a firstbit-width (e.g., X1 bits=7 bits), and the differential L1-RSRP may bereported with a second bit-width (e.g., X2 bits=4 bits).

A WTRU may be configured, indicated, and/or triggered to report one ormore beam groups. A maximum number of beams to report (e.g., N2) may bedetermined based on the number of beam groups for which a WTRU mayreport. For example, a WTRU may report a receiver beam group for which aWTRU reports one or more measurement values for Tx beams, and themaximum number of beams to report which are associated with a beam groupmay be determined based on the number of beam groups. One or more offollowing may apply. One or more threshold values for the number of beamgroups may be used. For example, a first maximum number of beans (e.g.,N2_max_1; N2≤N2_max_1) may be used if the number of beam groups isgreater than a predefined threshold. A second maximum number of beams(e.g., N2_max_2; N2≤N2_max_1) may be used if the number of beam groupsis equal to or smaller than a predefined threshold, A total number ofbeams to report (e.g., the total number of beams which may be reportedby a WTRU simultaneously) for one or more beam groups may be limited toa certain number. The limiting number may be configured, pre-determined,indicated, and/or pre-specified. For example, the total number of beamsmay be N2. If a WTRU reports one or more beams for a single beam group,the WTRU may report N2 beams for the determined beam group. If the WTRUreports one or more beams for N2 beam groups, the WTRU may report asingle beam for each beam group.

Beam reporting may be used or configured in various approaches oralternatives. In an approach or alternative, the WTRU may reportinformation about Tx beam(s) (e.g., a group of Tx beams) associated withthe TRP that can be received using a selected WTRU Rx beam set(s). A Rxbeam set may include a set of WTRU Rx beams for receiving a DL signal.The Rx beam set may be constructed in various ways. For example, a(e.g., each) Rx beam in a WTRU Rx beam set may correspond to a selectedRx beam in a (e.g., each) antenna panel. For a WTRU associated with morethan one WTRU Rx beam sets, the WTRU may report Tx Beam(s) associatedwith the TRP (e.g., the group of Tx beams) and/or an identifier of theassociated WTRU Rx beam set per reported TX beam. In an approach oralternative, the WTRU may report information about TRP Tx beam(s) on agroup basis (e.g., a WTRU antenna group basis). For example, the WTRUmay report one or more groups' with reporting a (e.g., one) Tx beam fora (e.g., each) group. A WTRU antenna group may include a receive WTRUantenna panel or subarray. For a WTRU associated with more than one WTRUantenna grows, the WTRU may report Tx beam(s) associated with a TRP(s)and/or an identifier of the associated WTRJ antenna group per reportedTX beam.

A TRP (or gNB) and a WTRU may transmit or receive different Tx and Rxbeams from a same antenna group(s). A TRP (or gNB) and a WTRU maytransmit or receive different Tx and Rx beams from a different antennagroup(s). TRP beams from the sane antenna group may be more correlatedwith similar angles of departure (AoD's) and/or zenith angles ofdeparture (ZoD's). TRP beams from different antenna groups may be moreuncorrelated. Different antenna groups may include one or more ofdifferent antenna panels or sub-arrays, same antenna panel(s) orsub-array(s) with using different polarizations, and/or same antennapanel(s) or sub-array(s) with most uncorrelated angles of arrival(AoA's) and zenith angles of arrival (ZoA's).

Tx or Rx beam sets may include beams that may be (e.g., tend to be)correlated, for example, beams from the same antenna group as describedherein. Tx or Rx beam sets may include beams that may be (e.g., tend tobe) uncorrelated, for example, beams from different antenna groups asdescribed herein.

A WTRU Rx beam set may receive gNB a TRP Tx beams. The WTRU Rx beam setmay receive gNB or TRP Tx beams simultaneously, if Tx beams tend to beuncorrelated (e.g., as described herein). The WTRU Rx beam set mayreceive gNB or TRP Tx beams simultaneously, if Tx beams tend to becorrelated, but the WTRU Rx beam set tends to be uncorrelated. The WTRURx beam set may receive gNB or TRP Tx beams non-simultaneously, if theWTRU Rx beam set tends to be correlated. e.g. from a same antenna group.

The WTRU may report some (e.g., all) unique, uncorrelated Tx and Rx beamset IDs and/or the Tx and Rx beam IDs associated with Tx and Rx beansthat are used. The WTRU may report part of uncorrelated, Tx and Rx beamset IDs, and the Tx and Rx beam IDs used based on certain criterion thatinclude one or more of a receive power metric exceeding certainthreshold, a correlation being less than a threshold, or the like.

There may be up to 256 or more=simultaneous beams belonging to one ormore TRP's, one or more WTRU groups, and one or more associated antennapanels. An approach may be used for reporting the TRP Tx beam receptionfor each WTRU Rx beam and/or beam sets while keeping the approachefficient.

A beam, beam set, or group of beams may be associated with (e.g.,designated as) a control beam, for example, NR-PUCCH. A control beamdesignation may be dynamic, semi-static, or in response to a requestfrom a TRP or a WTRU. A control beam (e.g., NR-PUCCH) may be used tosend control information (e.g., only send control information). Thecontrol information may provide an indication of the WTRU Rx beam setthat is configured for a WTRU response in one or more of a sector, abeam set, or a beam group. The indication of the WTRU Rx beam set may beconfigured during an initialization and/or as a part of an associationwith the network.

A WTRU antenna group may be associated with a single and/or multiple Rxbeam sets. A WTRU antenna group may be associated with multiple Rx beamsets. The WTRU antenna group may be associated with one or more antennapanels. A WTRU antenna group may have properties that indicate (e.g.,define) the WTRU antenna group's capability be supporting a WTRU reportof acceptable TRP 1× beams. The properties may include one or more ofthe number of antenna elements, polarization type(s), AoD/AoA,frequency/time resource(s), reciprocity, or the like. A WTRU report maybe sent for WTRU antenna groups based on the properties of the WTRUantenna groups. For example, a WTRU report may be sent for the WTRUantenna groups that have a particular property or a specific set ofproperties. For example, a WTRU report may be configured to report(e.g., only report) information for those WTRU's that have two or morepanels.

A WTRU may provide information related to coverage of either or both ofthe TRP Tx beam and the WTRU Rx Beam. A WTRU report may includeinformation on the beams having a minimal coverage. A beam, beam set, orgroup of beams, may be defined by the coverage that the beam, the beamset, or the group of beams achieve. Coverage may be determined based onfactors inducting one or more of the number of TRPs and/or WTRU beamsthat are received with an acceptable quality, beam and/or sector width,beam overlap, transmission power, and/or resource bandwidth.

A WTRU report may report the TX beams starting with the a beam(s) thathas the largest coverage, and then a beam(s) that has the next largestcoverage, finishing with a beam(s) that has the least acceptablecoverage. TABLE 7 provides an example of a measurement table withmeasured reference signal received power (RSRP) values. On the WTRU'sbeam measurement report, all or some of the table contents may bereported, for example, based on Rx beam set and/or Rx antenna group asdescribed herein.

The report may be based on Rx beam sets. An Rx beam set number thresholdT1 and/or Tx beam number threshold T2 may be configured. The first T1 Rxbeam sets (e.g., only the first T1 Rx beam sets) having the strongestRSRP (e.g., summation d all Tx beams and all Rx antenna groups withinthe Rx beam set) may be reported. For a (e.g., each) reported Rx beamset, the first T2 beams (e.g., only the first T2 beams) having thestrongest RSRP (e.g., summation of all Rx antenna groups for a Tx beam)may be reported along with the respective Tx beam indices for thereported T2 beams. A WTRU may have more than one Rx beam sets. The WTRUmay report TRP Tx beam(s) and identifiers of WTRU Rx beam setsassociated with the reported TX beam(s).

The report may be based on Rx antenna groups. For example, an Rx antennagroup threshold T3 and/or a Tx beam threshold T4 may be configured. Thefirst T3 Rx antenna groups (e.g., only the first T3 Rx antenna groups)having the strongest RSRP e.g., summation from all Tx beams and all Rxbeam sets) may be reported. For a (e.g., each) reported Rx antennagroup, the first T4 beams (e.g., only the first T4) having the strongestRSRP (e.g., summation of the Rx beam sets for a Tx beam) may be reportedalong with the respective Tx beam indices for the reported T4 beams. AWTRU may have more than one Rx antenna groups. The WTRU may report TRPTx beam(s) and identifiers of WTRU Rx antenna groups associated with thereported Tx beams.

The report may be based on both Rx beam set and Rx antenna group. A RSRPthreshold T5 may be configured. The measured RSRP(s) above the RSRPthreshold T5 may be reported, along with the details of thecorresponding Tx beam(s), Rx bean set(s) and Rx antenna group(s). Athreshold T6 for the number of RSRPs may be configured. The largest T6RSRP values may be reported with their respective Tx beam(s), Rx beamset(s) and/or Rx antenna group(s) corresponding to the largest T6 RSRPvalues.

The report may be WTRU-specific and/or may be configured based on WTRUcapability. For example, a report may be configured based on the numberof panels associated with the WTRU, and/or the number of antennaelements in a (e.g., each) panel. For example, if a WTRU is equippedwith one panel, the beam reporting may include Rx beam set-based beamreporting. When the number of antenna elements is limited, there may befewer number of Fx beams formed. The beam reporting may include Rxantenna group-based beam reporting. For example, the beam reporting maynot include Rx beam set-based beam reporting.

The reporting may be based on the correlation between the Rx beam setsand Rx antenna groups and/or received power threshold such as RSRP orCSI. The report may include uncorrelated RSRP values. The report mayonly include uncorrelated RSRP values if the correlation between the Rxbeam sets and Rx antenna groups is taken into account fa reporting. Forexample, (Rx beam set 1, Rx antenna group 1) may be spatially correlatedwith (Rx beam set 2, Rx antenna group 2). Although both of their RSRPvalues for Tx beam 3 may be higher than a reporting threshold, a RSRPvalue (e.g., only one RSRP value) may be reported. The reported RSRPvalue may combine the RSRP values from the correlated (Rx beam set. Rxantenna group), for example, (Rx beam set 1, Rx antenna group 1) and (Rxbeam set 2, Rx antenna group 2).

TABLE 7 shows an example of a beam measurement table. The Tx beam indexmay be represented and/or reported in terms of any or any combinationof: CSI-RS resource IDs, a Tx antenna port index, a combination of Txantenna port index and a time index, reference sequence index, etc.

TABLE 7 an example of a beam measurement table Tx Tx Tx Tx beam 1 beam 2beam 3 . . . beam n Rx beam set Rx antenna RSRP RSRP RSRP RSRP 1 group 1Rx antenna RSRP RSRP RSRP RSRP group 2 Rx beam set Rx antenna RSRP RSRPRSRP RSRP 2 group 1 Rx antenna RSRP RSRP RSRP RSRP group 2

Beamforming processes in NR may include beam acquisition, beamadjustment, and/or beam recovery. One or more of the beam acquisition,beam adjustment, and/or beam recovery may be achieved, for example, byDL L1/2 beam management processes including P-1/P-2/P-3. Group-based DLL1/L2 beam management processes may be performed for beamtracking/refinement within a group or multiple groups, for example, toreduce signal overhead and latency. An example of an L1/L2 beammanagement process using beam grouping may be described herein.

P-1 beam management may be performed. The TRP and WTRU may perform a P-1beam management process, e.g., to identify coarse transmit and receivebeams. In the P-1 transmit process, the TRP may transmit and/or cyclethrough the TRP's beams (e.g., 1, 2, 3 and 4 illustrated in FIG. 22 )with the WTRU antennas set as quasi-omni. The WTRU may feedback theWTRU's best beam to the TRP. During the P-1 process setup, the TRP mayindicate that the set of beams used are in the P-1 group. The WTRU mayfeedback the best-N beams to the TRP with an indication to group thebeams together for possible fall-back beam scanning. This allows forWTRU-specific grouping of the beams. This is illustrated in FIG. 29 asbeam 1 in procedure items 1 and 2.

In the P-1 receive procedure, the TRP may transmit while the WTRU cyclesthrough the WTRU's beams (e.g., 1, 2, 3 and 4 illustrated in FIG. 22 ).The TRP may transmit using quasi-omni beams. The TRP may use a beam(s)identified during the P-1 transmit procedure if an analog feedback hasoccurred. This is illustrated in FIG. 29 as Rx beam 3 in procedure items3 and 4. The WTRU may feedback the Rx beam index to the TRP or initiatea transmission to the RX indicating a successful completion of the P-1procedure. The feedback may be done through the RACH.

Multi-group based P-2/P-3 beam management may be used. The TRP and WTRUmay perform transmit and receive beam refinement using the P-2 and P-3beam management procedures. The P-2 refinement procedure may be for thetransmitter while the P-3 refinement procedure may be for the receiver.

Beam grouping for P-2/P-3 procedure may be performed. The beamrefinement procedures may be based on an exhaustive search of some orall possible beams (e.g., FIG. 25 ). The beam refinement procedures maybe based on a series of searches on beams of changing resolution (e.g.,FIG. 23 , FIG. 24 , FIG. 25 for equal bandwidth: FIG. 26 and FIG. 27 forunequal bandwidth). The beam refinement procedures may be based on agroup(s) of beams with unequal bandwidth (e.g., FIG. 28 ).

The TRP and WTRU may perform P-2/P-3 beam refinement on a series of beamgroups of increasing resolutions (e.g., 16 beams as shown in FIG. 23 ,64 beams as shown in FIG. 24 and finally 256 beams as shown in FIG. 25), for example, rather than performing a beam refinement using anexhaustive search on the beams of the desired beam group (e.g., 256beams as shown in FIG. 25 ), In this example (e.g., simplified), if wewere to perform a permutation of all possible beams, in the exhaustivesearch scenario and assuming that the P-1 procedure has identified theP-1 beam with 64 beams for refinement, we would have 64×64 beam pairs tosearch through. In the scenario with multiple resolutions, we may have3×16×16 beam pairs to search through. This may reduce time used (e.g.,an overall time needed) for beam search procedure and/or may increasebeam refinement efficiency.

The TRP and the WTRU may perform P-2/P-3 beam refinement on a series ofbeam of uneven or varying resolution(s). In an example, this may occurif additional information such as the location of the WTRU may beavailable. In this case, the beam group may have a refined beam(s)around an angular location pointing toward a dense WTRU location(s)and/or larger beams elsewhere. This is illustrated in FIG. 26 and FIG.27 . In an example, this may occur in a scenario where the TRP may pointto traffic of varying types. A pattern such as one shown in FIG. 26 andFIG. 27 may occur if a first quadrant of the TRP points to a hotspotwhile the other quadrants point to a road with WTRUs of higher Dopplerpresent. In one example, this may occur in scenarios where the TRP maydesire to sweep a beam space (e.g., the entire beam-space) with beams ofvarying beamwidth as show in FIG. 28 .

P-2/P-3 procedure for group-based beam may be performed. For P-2/P-3Group 1, the TRP may initiate a P-2 transmit beam refinement procedureby sending a measurement signal on a beam (e.g., each of the beams) inthe group (e.g., corresponding to sub-beams with beamwidth of 22.5degrees as illustrated in FIG. 23 ) with the WTRU setting the WTRU'sreceive beam to the beam identified in the P-1 beam management procedure(e.g., beam 3). The measurement to decide the best beam may be based onone or more of the beam-based synchronization signals, beam measurementsignals, or WTRU-specific beamformed measurement signals.

The WTRU may feedback the best Tx beam for beam group 1 (e.g., Tx beamP-2: G1:Tx=2) as shown in FIG. 30A-30B, procedure items 1 and 2) aid/orrequest for a P-3 receiver beam refinement procedure. Tx beam P-2: G1:Tx=y may be the beam y in group 1 estimated from the P-2 procedure. TheWTRU may feedback the best N Tx beams for beam group 1 and acorresponding group number to allow for beam group resolution fall-back,for example, in the case of a loss of the link. In beam resolutionfall-back, the WTRU/TRP may request for beam tracking/sweeping within aspecified group. The TRP may send a measurement signal with the Tx beamset to Tx beam 1, 2 for four measurement durations and the WTRU maycycle through a (e.g., each) beam within the resolution. The WTRU mayfeedback the best Rx beam, for example, (P-3 G1; Rx=3) as shown in FIG.30A-30B, procedure items 3 and 4.

For P-2/P3 group 2 and group 3, the TRP and the WTRU may perform thesecond and third P-2/P-3 beam refinement procedure in which beam groupsof increasing resolution are used. The TRP and the WTRU may do this bychanging beam groups and/or selecting sub-groups based on the feedbackfrom a previous refinement group. In the example in FIG. 30A-30B, in thenext refinement group, the refinement may correspond to the beam groupwith sub-beams of beamwidth of 5.625 degrees as illustrated in FIG. 24 ,with the WTRU setting the WTRU's receive beam to the beam identified inthe first group refinement (P-3 G1: Rx=3). The TRP and the WTRU mayidentify the best Tx and Rx beams for beam group group 2, for example,(P-2 G2: Tx=1 as shown in FIG. 29 , procedure items 5 and 6 and Rx beamP-3 G2: Rx=4) as shown in FIG. 29 , procedure items 7 and 8.

Further refinement may occur at the next group of resolution in whichthe refinement may correspond to the beam group with sub-beams beamwidthof beamwidth 1.06 degrees as illustrated in FIG. 25 , with the WTRUsetting the WTRU's receive beam to the beam identified in the firstgroup refinement (Rx beam P-3 G2: Rx=4). The TRP and the WTRU mayidentify the best Tx and Rx beams for group 3, Tx beam (e.g., Tx beam P2G3: Tx=3 equivalent to beam 19 of the 64 beams in the P-1 beam as shownin FIG. 29 , procedure items 9 and 10) and Rx beam (e.g., Rx beam P-3G3: Rx=3 equivalent to beam 48 of the 64 beams in the Rx P-1 beam asshown FIG. 29 , procedure items 11 and 12). The beam(s) may be anantenna waveform vector.

This may allow for a more efficient beam sweep than an exhaustive searchand/or may allow for easy beam fall back, for example, during periods ofa link loss. This procedure may be reversed for UL beam management withthe WTRU as the initiator and the TRP as the responding element. In thiscase, the procedures P-1, P-2 and P-3 may be replaced by thecorresponding uplink procedures U-1, U-2 and U-3.

In the event of a loss in the link or transmit receive pairs, the TRPand/or the WTRU may fall hack to a beam group with a larger resolutionfor a quick recovery. This may allow for a more robust link and/orfaster link recovery as the refinement procedure (P-2, P-3, U-2, or U-3)may start from the desired beam group as described herein rather thanperforming an exhaustive search over all beams.

Waveform selection for beam management may be performed. Mechanisms maybe provided for waveform selection for beam management. A transmissionmay use one of several types of waveforms inducing CP-OFDM, CP DFTsOFDM,or UW/GIRT DFTsOFDM. A waveform type may be associated with a beam groupto a particular WTRU type. A WTRU may support a beam's full or partialreciprocity and/or may support specific waveform capabilities. When aTRP queries a WTRU for inclusion in a beam group, the TRP may receivethe WTRU's capabilities response(s). If the WTRU supports beamreciprocity, the TRP may use the beam reciprocity to enable a particularwaveform type at the TRP and/or instruct the WTRU to use the same typeof waveform(s).

If a beam group is in a cell edge region, it may be desirable for thewaveform to be set to DFT-s-OFDM. The TRP may be configured to receive aDFT-s-OFDM waveform. Some or all of the WTRU's allocated to a beam groupconfigured for DFT-s-OFDM reception may use a DFT-s-OFDM waveform. Forexample, all of the WTRU's allocated to a beam group may be configuredwith DFT-s-OFDM. Whether a CP-OFDM, DFT-s-OFDM, or other type ofwaveform is used, it may be assumed that the configuration informationfrom the WTRU may be received irrespective of the waveform type in use.

Although the solutions described herein consider LTE, LTE-A, New Radio(NR) or 5G specific protocols, it is understood that the solutionsdescribed herein are not restricted to this scenario and are applicableto other wireless systems as well.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, WTRU, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A wireless transmit/receive unit (WTRU),comprising: a processor and a transceiver which are configured to:receive a first channel state information reference signal (CSI-RS)configuration message, wherein the CSI-RS configuration message includesinformation indicating a first group of beams associated with a firstlevel of beam reporting that uses a first cycle, receive a second CSI-RSconfiguration message, wherein the second CSI-RS configuration messageincludes information indicating a second group of beams associated witha second level of beam reporting that uses a second cycle, and whereinthe first level of beam reporting differs from the second level of beamreporting, send a first report in accordance with the first cycle,wherein the first report is based on measurement information associatedwith the first group, wherein the first report comprises a referencesignal received power (RSRP) for a representative beam, and therepresentative beam is one of the beams in the first group, and send asecond report in accordance with the second cycle, wherein the secondreport is based on measurement information associated with the secondgroup, wherein the second report comprises a differential RSRPassociated with a RSRP for a first beam in the second group and areference RSRP associated with a second beam in the second group.
 2. TheWTRU of claim 1, wherein the reference RSRP associated with the secondbeam has a largest measurement value compared to RSRPs of the beams inthe second group.
 3. The WTRU of claim 1, wherein the RSRP of therepresentative beam has a largest measurement value compared to RSRPs ofthe beams in the first group.
 4. The WTRU of claim 1, wherein theprocessor is further configured to determine the RSRP for therepresentative beam based on a beam reference signal, wherein the beamreference signal comprises a channel state information reference signal(CSI-RS) or a synchronization signal (SS)/physical broadcast channel(PBCH) block.
 5. The WTRU of claim 1, wherein the first report includesa channel state information (CSI) resource index associated with therepresentative beam.
 6. The WTRU of claim 1, wherein at least one of:(1) the first CSI-RS configuration message includes informationindicating the first cycle, and/or (2) the second CSI-RS configurationmessage includes information indicating the second cycle.
 7. The WTRU ofclaim 1, wherein one or more beams in the second group are the same asone or more beams in the first group.
 8. The WTRU of claim 1, whereinthe second group of beams are different than the first group of beams.9. A method, comprising: receiving a first channel state informationreference signal (CSI-RS) configuration message, wherein the CSI-RSconfiguration message includes information indicating a first group ofbeams associated with a first level of beam reporting that uses a firstcycle; receiving a second CSI-RS configuration message, wherein thesecond CSI-RS configuration message includes information indicating asecond group of beams associated with a second level of beam reportingthat uses a second cycle, and wherein the first level of beam reportingdiffers from the second level of beam reporting; sending a first reportin accordance with the first cycle, wherein the first report is based onmeasurement information associated with the first group, wherein thefirst report comprises a reference signal received power (RSRP) for arepresentative beam, and the representative beam is one of the beams inthe first group; and sending a second report in accordance with thesecond cycle, wherein the second report is based on measurementinformation associated with the second group, wherein the second reportcomprises a differential RSRP associated with a RSRP for a first beam inthe second group and a reference RSRP associated with a second beam inthe second group.
 10. The method of claim 9, wherein the reference RSRPassociated with the second beam has a largest measurement value comparedto RSRPs of the beams in the second group.
 11. The method of claim 9,wherein the RSRP of the representative beam has a largest measurementvalue compared to RSRPs of the beams in the first group.
 12. The methodof claim 9, further comprising: determining the RSRP for therepresentative beam based on a beam reference signal, wherein the beamreference signal comprises a channel state information reference signal(CSI-RS) or a synchronization signal (SS)/physical broadcast channel(PBCH) block.
 13. The method of claim 9, wherein the first reportincludes a channel state information (CSI) resource index associatedwith the representative beam.
 14. The method of claim 9, wherein atleast one of: (1) the first CSI-RS configuration message includesinformation indicating the first cycle, and/or (2) the second CSI-RSconfiguration message includes information indicating the second cycle.15. The method of claim 9, wherein one or more beams in the second groupare the same as one or more beams in the first group.
 16. The method ofclaim 9, wherein the second group of beams are different than the firstgroup of beams.